edit: multiple people answered in the comments! problem solved! hooray!
original content follows:

literally nothing changes on my profile when i toggle it on and off

the fact that it toggles a query param makes me think that it isn't a global setting (and testing shows that it doesn't hide the account's replies in comment section)

i know cohost has comments but you can't see them on people's profile from what i can see

i feel like i'm losing my mind