unable to do any connection after changing hostname(probably)

I needed to change hostname on ubuntu 22.04. I did it the old way, by manually editing /etc/hostname and adding

127.0.0.1   localhost127.0.1.1   my-host-name

into /etc/hosts not knowing about hostnamectl. It surely might be something else as well, but I'm not aware of it. Just reinstalled yesterday, and this morning nothing dns-related works.

I can ping, or do ssh connection using ip. I can print on local network, but it's exceptionally slow. Trying dig -t a google.com prints communications error to 10.128.32.11

I already tried:

• hostnamectl set-hostname my-host-name
• systemctl restart NetworkManager
• resolvectl flush-caches
• systemctl restart systemd-resolved.service

during this, I noticed, that resolvectl dns returns some global dns servers I didn't asked for. That's probably the reason, not sure. Can anyone advice how to fix?

(note: company uses some super-obsoleted vpn provided, which requires NetworkManager, that's why I was working with that in first place)