Get access to your instance history and errors by loggin in.
Create a random value, and its corresponding SHA256 hash:
Run this in bash: uuidgen -r | tee >(tr -d $'\n' | sha256sum)
The output is like this:
00000000-0000-0000-0000-00000000000012B9377CBE7E5C94E8A70D9D23929523D14AFA954793130F8A3959C7B849ACA8
The first line is your random value, and the second line's hex part is the hash.
For your instance nitter.example.com, either:
create a new TXT record with the name status-d420.nitter and the value 6c9872185d6975f0f51d7d16a6428aadb1df494af0f68166f790ef0d51b0bc8f
Verify that dig -t txt status-d420.nitter.example.com resolves
OR: create a file https://nitter.example.com/.well-known/status-d420 with the content 6c9872185d6975f0f51d7d16a6428aadb1df494af0f68166f790ef0d51b0bc8f
License: AGPL3