There seems to be some caching problem with the normal/mute/ignore button in the profile.
If I use it to change a “normal” user to “muted” it shows all other users also as muted in their profile. Reloading the other profile (F5) fixes the issue.
Example
User #1 current setting “normal”:
Change to “muted”:
Open User #2 profile, also “muted”, although he isn’t:
Reloading the profile fixes the issue:
Found with Discourse 2.5.0, Chrome 83.