[2024] No supported authentication methods available

Good day. I was working on my AWS EC2 instance using WinSCP, until one moment where it tried to reconnect and this error showed up:

No supported authentication methods available (server sent: public key, gssapi-keyex, gssapi-with-mic. Using username "[username]".
Server refused our key. Authentication failed.

As far as we are aware, no one was modifying any permission, and there is no expiration in the ppk file that we used to connect. It was working fine 10 minutes before this error showed up. I have PuTTY up and still running despite WinSCP not connecting to the server. What should I do?

Can you open new connection using PuTTY?