This is still broken on ps5 Realms on the latest update. I play on a Realms plus world with my family and this is making it impossible to play with my family in a way that properly saves my progress. If it doesn't get resolved soon I will be downloading my Realms world and then canceling the subscription.
I have version 1.21.92 Bedrock on Playstation PS5 and it is still having the second player join as first player (1) even though the second players Playstation username is in the top right corner. It's also interesting that Mojang keeps resolving the Playstation platform version of these bugs and links them back to this one that's for XBOX.
Still an issue on ps5 with realms.