Hi everyone!
We reached out to PlayStation for you all, for the next-gen upgrade you may need to do an extra step to make sure your PS5 is running the PS5 version and not the PS4 version of your game. In the '...' menu you can change this so that your console will run the PS5 version instead. There's more information about it at this help article to give you a step by step on how to resolve it:
https://www.playstation.com/en-us/support/games/upgrade-ps4-game-to-ps5-version/
For the issues some of you have had with DLC, that should now be resolved and if it isn't, checking the above process should help. If it doesn't please let me know so we can investigate further!
thanks for your patience, time to get back to your parks soon