Fedora33 implements higher security standards, not only for server side, but even when it comes to client connections.
This includes more restrictive rules on accepted Ciphers, Kex (key exchange) algorithms, etc.
Unfortunately this leads to situation in which you can no longer connect to older hosts, like CentOS5, some switches, for example JunOS12.
If you start getting the similar SSH errors:
debug1: send_pubkey_test: no mutual signature algorithm
debug1: kex: algorithm: (no match)
Unable to negotiate with xx.xx.xx.xx port 22: no matching key exchange method found. Their offer: diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1