Hey Aliete_ad,
Just to clarify, progress is stored on the EA account level, not on individual platforms like PlayStation, Xbox, Steam, etc. Because of that, if you unlink your platform and link it to a different EA account, you'll lose access to that progress.
With that said, have you unlinked and relinked your PS5 account to the EA account your Xbox was linked to? If so, or if you're missing either the Xbox or PS5 progress now that both accounts are confirmed to be linked to the same EA account, that would suggest that one of those platform accounts was previously linked to another EA account.
You will need to re-link your platforms to their original EA account to try restoring any missing progress. This would refer to both the EA account your PS5 and Xbox accounts were linked to, respectively. If you've already re-linked the original accounts and the progress has not returned, it would be lost permanently and unfortunately cannot be recovered.
If you're running into any trouble getting the original accounts re-linked, please contact support directly so they can take a look. Thanks!