Sorry for my late answer.

This request has been added to the tracker:
https://winscp.net/tracker/1952
You can vote for it there.

We will definitely upgrade to PuTTY 0.75 once it is available. If there's a popular demand, we may upgrade to a snapshot even before the 0.75 release.

Hi,

sshd in fedora33 does not accept ssh-rsa by default. The error is 'Server refused our key.'
Putty implemented rsa-sha2-512 in the latest master (after 0.74 release).
Please consider updating it to some snapshot or when 0.75 is available.