Safest, encrypted, anonymous email service / software in 2023

Nothing on the web is secure or safe. The weakest link is always the best route if attack. Usually phones.

I think people could come up with more/better answers if you described your use-case(s) in generic terms. e.g. Is this for a small group of friends, mailing lists, feedback to businesses, anonymous tips to governments, etc...

Important for me is that I can access this email on the web, but also on the deepweb, as I’m in a country where they apply censorship to certain websites.

Try Tutanota, it's the best for anonymity & doesn't even ask for a phone number to sign up: https://tutanota.com/blog/posts/anonymous-email

Can you use Protonmail in your country? It is considered very safe and they also provide a good VPN that is free.

Skiff is good too: https://skiff.com/