HI @Untpunter
To confirm you had your Xbox account linked to an EA account (Account 1), and a PSN account linked to a separate EA account (Account 2).
When you unlink your Xbox account you will lose all items and progress as they are stored at the EA account not the platform account. So when it was linked to the EA account (account 2) that was tied with your PSN, it would have had no progress.
This is working as intended and is something that happened before Cross Progression with Apex Legends was introduced.
For more information check out the links I posted above.
For the PSN Account, if that is now your main account and is missing items, progress, skins, etc. Please let us know what specifically you are missing.
While some items, stats, and progress won't update if you are looking for any from another platform, your skins, currency, etc will still be there.
Thanks!