Problem Package (fedora): firefox.x86_64 86.0-2.fc33
I was getting:
Unsupported hash algorithm used by TLS peer.
Error code: SSL_ERROR_UNSUPPORTED_HASH_ALGORITHM
Cannot communicate securely with peer: no common encryption algorithm(s).
Error code: SSL_ERROR_NO_CYPHER_OVERLAP
...on some major sites. Nothing on the internet seems to fix it.
In the end I just downloaded the firefox bzip from Mozilla ( https://www.mozilla.org/en-GB/firefox/download/thanks/ ) and extracted it into /usr/lib64
wget https://ftp.mozilla.org/pub/firefox/releases/86.0/linux-x86_64/en-GB/firefox-86.0.tar.bz2 -O - | tar -jxv -C /usr/lib64
Now everything works.
[Update: An update from Fedora also fixed it. Namely 86.0-7.fc33.]