How is Salazars curse linked with Sparrow's compass

I don't believe it is a plot hole at all.

Jack may have given away the compass before but he had never betrayed it. The two things are mutually exclusive.

From this source:

• In Dead Man's Chest, Jack gave away his compass to Elizabeth and convinced her that the only way to find Will Turner was to find the Chest. During the DVD commentary, writers Terry Rossio and Ted Elliott explained that the compass only points in Jack's "direction" - not at Jack himself - when Elizabeth holds it and on Isla Cruces. It continually points at the location of the Chest, despite Elizabeth believing it is pointing at Jack. Therefore, the compass was actually faithful to what Elizabeth wanted at that moment.
• In At World's End, Jack gives the compass to Will, who probably doesn't use it, but remains the owner of the compass until he gives it to Beckett, who then returns it to Jack. However, Jack gave it to Will to save himself, thus breaking his loyalty to the compass.
• In On Stranger Tides, Jack gives away the compass to Gibbs, who finds the Black Pearl. As Jack mentioned that it would lead him to his freedom, the compass led him to Blackbeard's ship, which was the nearest means of getting off the island. There he probably had a change of heart, robbed the miniature ships and sailed back to the island to rescue Jack.

And my arguments against each point:

• He gave it to Elizabeth meaning to get it back only so he could find the chest, it wasn't to remain with Elizabeth forever.
• He gives it to Will so that he can find them again where Jack had all intentions of getting it back
• Haven't seen this film for a while so will need a refresher!

When he gives it up and Salazar is released he is finally betraying the compass as he has no intentions of getting it back as he has given up.

Lastly, I would argue again that the origins of the compass are clear. He bartered for the compass, something happened (grey area here) and then he inherits it.

It's generally considered a plot hole.

Not only has Jack betrayed the compass before...

• In Dead Man's Chest, Jack gave away his compass to Elizabeth and convinced her that the only way to find Will Turner was to find the Chest. During the DVD commentary, writers Terry Rossio and Ted Elliott explained that the compass only points in Jack's "direction" - not at Jack himself - when Elizabeth holds it and on Isla Cruces. It continually points at the location of the Chest, despite Elizabeth believing it is pointing at Jack. Therefore, the compass was actually faithful to what Elizabeth wanted at that moment.
• In At World's End, Jack gives the compass to Will, who probably doesn't use it, but remains the owner of the compass until he gives it to Beckett, who then returns it to Jack. However, Jack gave it to Will to save himself, thus breaking his loyalty to the compass.
• In On Stranger Tides, Jack gives away the compass to Gibbs, who finds the Black Pearl. As Jack mentioned that it would lead him to his freedom, the compass led him to Blackbeard's ship, which was the nearest means of getting off the island. There he probably had a change of heart, robbed the miniature ships and sailed back to the island to rescue Jack.

But even the origins of the compass are not coherent.

[Jack] bartered [the compass] from the voodoo mystic Tia Dalma and later inherited from his captain.

A wild guess here is that Jack's previous captain, when he died and gave Jack the compass, curses Salazar (the man who killed him). However, this is pure speculation, and as far as I know, no official word has come out about this.

The compass releases your greatest fear, which in Jack Sparrow's case is Salazar

40 minutes into Pirates of the Caribbean: Salazar's Revenge (2017), Captain Hector Barbossa visits a bald witch, Shansa, to consult with her for a solution to his problem of undead sailors having "taken command of the sea".

Once Barbossa confirms that his treasure is "worth dying for", Shansa reveals some information about the compass:

SHANSA: Jack held a compass which points you to the thing you desire most. But, betray the compass... And it releases your greatest fear.
_{—Pirates of the Caribbean: Salazar's Revenge (2017)}

The compass is not linked to Salazar or his curse in any special way, except that Jack's greatest fear, at the time of betraying it, happened to be Salazar.

This becomes even more clear when we take a look at the flashback scene in which we see Jack being given the compass by his former captain, Captain Morgan:

MORGAN: It's up to you now, Jack. This compass points towards what you want most. Never betray it.
_{—Pirates of the Caribbean: Salazar's Revenge (2017)}

Morgan had this magical compass and was aware of its special relationship (never to betray it) before Salazar was ever destroyed at the Devil's Triangle, and before Salazar was cursed, so it makes no sense that it would have an inherent, special relationship to one particular curse that would happen in the future, long after the inception of the magical compass.

I think what is missing in the idea of what Jack fears most is not just Salazar himself, rather it is death. Throughout the PotC series Jack is always looking for a way to prolong his life. He wants to essentially live forever on the seas as Captain Jack Sparrow. Fountain of youth and Davey Jones heart are the examples. We even get a glimpse of it in CotBP when it takes the Aztec gold coin and finds it interesting even if only for a moment. Jones' main saying is "Do you fear death?" Salazar even says that once he sees the light that death will come for him. Again, death is the common idea of each film as well as life.

Well, in the first 3 movies, Davy Jones was alive, and I would say it's a safe bet to say, that Jack feared Davy Jones and his judgement the most, during this time. So maybe him betraying the compass during this time just put Davy Jones closer to Jack's trail than he anticipated. I gotta say I really do hate the whole thing with Salazar and how he was released by the compass... Will Turners sons ship just happens to float into the Devils Triangle, which allows Salazar's to murder everyone on board, save said son... Who of course has a link to Jack Sparrow... Then Salazar who can apparently see into the future, knows Jack is going to give his compass away, very soon! Then tells Henry to tell Jack he's coming for him... The army of dead dudes never would have been after Jack if he never gave away the compass.... I just... I don't know man... Its all just to much for me I guess. It's just way to finicky...