Text-To-Speech notifications continue to arrive when the channel is muted. Please make these settings affect voice notifications.

When you enable the "Text-To-Speech Notifications" option, the channel mute settings do not work. This is very disturbing, in case you want to hear what is being written on one channel, but there is always spam on the other. By the way, none of the settings work - neither server or channel mute, nor server notification settings.
Please make sure that at least one setting affects voice notifications.