Hey Aljalade909,
Progress is stored on the EA account level, not on individual platforms like PlayStation, Xbox, Steam, etc. This means if you link your platform to a different EA account, you'll lose access to that progress and it will appear to have reset. Progress cannot be moved between different accounts.
In your situation, if you don't care about the progress that's been made on this newer EA account connected to Steam and only care about the progress on your older connected EA + PSN accounts, what you're describing is definitely possible. Unlinking your Steam from its own EA account will cause you to lose access to the progress on that EA account, and you'll instead have access to whatever progress was made on that old EA account your PSN was linked to already.
If you haven't recently linked those platforms you should be able to move them on your end, but if something was linked or unlinked incorrectly it may be worth contacting support to see if the original platforms can be re-linked.