When I click Notifications icon in the top right corner or right click chat (group, channel in chat list) and then select Mute (Forever, the bug appears only on this option) nothing happens on K (but it does work on Z), chat remains unmuted. If I turn off notifications in the Profile right panel it works. Cleared cookies but it didn't help. If I Unmute by the above methods it works.
Telegram Web 1.5.0 K, Chrome 105