The 4 digits on that name (#5366) don't match the digits on your profile (#4449). This could mean you've signed into an alt account on Steam you created with the same name as the one linked to your profile. If that's the case, you just need to sign out of Steam and sign in with the correct account's login. If you're having trouble with that, see Steam Support for assistance. The other possibility would be if your Steam account recently participated in a Cross Save that you disabled within the last 90 days. If that's the case, then it cannot participate in your current Cross Save until the 90-day cooldown expires.

No, deleting the game would not fix anything. First, did you use your Steam account in another Cross Save within the last 3 months?

Try signing out of Steam and signing back in by manually entering your login credentials. If you see the same character you're currently seeing when launching D2, open Bungie.net in an Incognito browser window then sign in using the same credentials you entered on Steam. If you see your correct PS4 characters on Steam, then you were signed into an alt Steam account by mistake. This commonly happens when Steam players use an email to create an account and create another with the same email without realizing it. This can be avoided by signing in with your unique Steam profile name. If you get signed into [url=https://www.bungie.net/7/en/User/Profile/3/4611686018532961051?bgn=Eden]this profile[/url] on Bungie.net, that also means you have 2 Steam accounts. In that case, you will need to figure out the correct login to enter on Steam. If you're having trouble with it, contact Steam Support for help.