Zedeus is the creator of Nitter and he said "Nitter is dead" a couple of days ago now.
From the same thread -
Currently, Nitter uses guest accounts to access content on Twitter. Guest accounts expire after 30 days (IIRC) of them being created. Guest account creation has been shut off, so all existing guest accounts will be dead after 30 days max. Nitter instances with working guest accounts are not dead yet, but they will be.
You linked to Zedeus's GitHub.
Zedeus is the creator of Nitter and he said "Nitter is dead" a couple of days ago now.
From the same thread -
https://github.com/zedeus/nitter/issues/1155
Your suggested resolution is to take down the remaining mirrors.