I’m having the same issue not with STEAM but an old PlayStation Network account. I unlinked it from my EA account years ago but it’s still tied in the background. I have been using STEAM for many years so I didn’t run into any difficulties, but now I have switched over to the PS5 (cost saving on hardware upgrades) I can’t login to my EA account from 2009 using my PlayStation Network account that was created in 2014 because it claims another ID is present on the account.
I have reached out to support via the live chat, had the case escalated but they sent me a generic response today after 4 days of waiting. I have replied to the email but I think I may need to go down the live chat route again. It’s frustrating, what’s the point of offering an unlink option if it’s still present in the background on EA’s end? That PSN ID that is attached has no bearing on anything. If I was unlinking my STEAM account for example I would be losing out on a lot of purchased games, but not with that really old PSN ID.
I have purchased 5 EA titles since switching over to PlayStation so they need to get it sorted. 2 digitally and 3 physically.