It’s an extension called Auto Tab Discard
I also use auto tab discard. This is the only tab to which it prepends a z.
Wow! I just logged in here to check for responses, and found all these helpful and useful replies! Thank you all, you are great!
AFAIK, the Auto Tab Discard Addon basically only rewrites the tabtitle with the 💤 , since there is no other way for addons to add custom icons to the tabs at the moment, just fyi.
I use the “Auto Tab Discard” Addon which can be configured to do this.
There’s a plugin called auto discard. I’ve used it before but it can cause certain issues with other plugins like simple tabs (it kept duplicating tabs because of the zzzs in front of the name)
Autotabdiscard plugin
There might be a config for it, but I use a plugin called auto tab discard. Very configurable. Saves ram too