I see. Do the mods you've installed manually look the same as the ones you've subscribed to (which I assume work for you), in terms of what is in the Documents/Paradox Interactive/Stellaris/mod/ folder? As maybe you can tell I have no experience in manually installing mods ...
Let's try forcing an update of the launcher.
Download the installer package: https://forumcontent.paradoxplaza.com/emailsignatures/2021.5-mac-prod.zip
Unpack the file you just downloaded and place the three files in the Steam folder for the game you're having issues with. If asked if you want to replace already existing files click "yes" - that's a sign you are in the right place!
Then please repeat the launcher reinstall procedure (ie deleting that folder) from before.
Good luck with that!