What "page related to 5.20" are you referring to?
WinSCP 5.20 beta can be downloaded from:
https://winscp.net/eng/download.php?n=5.20
Beta versions are not available in Microsoft Store.
Thanks for supporting WinSCP development.

Dear Martin

Thank you for your email.
I open the page related to 5.20 (beta) version, but I couldn't find where or how to download 5.20. I saw that as a donor, I can access nightly upgrades (I installed from MS Store, I think this becomes me as donor, I guess). Please, could you be more specific to point me directions?
Thank you for your attention.

My best regards

Please upgrade to WinSCP 5.20 beta:
https://winscp.net/tracker/1952

Or (re-)enable ssh-rsa in your OpenSSH installation.

Dear

Since I updated openssh from 8.6 to 8.8, WinSCP (last release) cannot authenticate.
I found that problem is on WinSCP because:
1) transfers using openssh-8.8 in Unix environment (tested with FreeBSD and Debian) worked fine, without problems.
2) communication (terminal emulating) using PuTTY, is ok
3) files transfers using Bitvise (importing the key used in WinSCP) worked well too.

Thus, I concluded that the problem is on the way (newly) by which WinSCP performs authentication process.

Please, anyone has noticed this problem too?

Thanks in advance for your attention

Eduardo