We typically do not trust email as a verification for disabling 2FA. There is a process documented at https://wikitech.wikimedia.org/wiki/Password_reset#For_users that can be used to establish higher trust using ssh.

Instructions for actually disabling 2FA on a Developer account are at https://wikitech.wikimedia.org/wiki/Password_reset#Wikimedia_or_wikitech_two_factor_authentication_removal

I've got two keys saved as "wikitech" on my backup disk.
However, I can't get SSH access with them.

Can someone verify my shell login? I've tried Szczot3k and szczot3k.

When I'm trying to connect with U: szczot3k and the newer key it closes the connection.
I've got access to SUL user:Szczot3k.

~ >>> ssh szczot3k@bastion.wmflabs.org                                                                                                                                
Enter passphrase for key '/home/fkszczot/.ssh/bastion.wmf': 
Connection closed by 185.15.56.13 port 22
~ >>> ssh Szczot3k@bastion.wmflabs.org                                                                                                                           [255]
Enter passphrase for key '/home/fkszczot/.ssh/bastion.wmf': 
Szczot3k@bastion.wmflabs.org: Permission denied (publickey).

RSA key fingerprints:
2048 SHA256:lLkMtP87o4esR/7X5lQEcoHkVr6YCzKQQORKvB8lozQ szczot3k@wikitech (RSA) [Newer]
2048 SHA256:IHaZshRSt3KtrUAE2XSb9+pqKF6JizQNHXA78vYX6d8 ((my email)) (RSA) [Older}

The User:Szczot3k Developer account has a shell account name of 'szczot3k'. The account is configured to allow ssh using this public key:

ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCxpn8NIXymJDxS++xlzOymXIqb8u6l+7aNq1xQEsnLTxdXmHrMxZl5IUEjQYVGey0IPqscGZL4n2bRg5RsResP0QgdqZ3GRNLMPD+6MQr2j+a0CMQLFIsHLv9UoTOH/WYIrHoAiL7Z/N39hjY4WlhTXEfUdpOVJ8VvJ9ZysC/WR4DJ9pg/XDLTWJVzcA+TIGFFKU+/qZXnZrfCRe1Bf2JdHMTmpINTpoWeZ6UYFLEEnEt+11fyAOGKtD7MFXOSNvvJdzjZUgF/ArgYddks10QiSr87jHGRgL5c6Q71+mvwQCrsiascE/P323gN1KldoWMyNKOy2DdDL6ASL8iRlU7D szczot3k@wikitech

In T260096#6376239, @Szczot3k wrote:

When I'm trying to connect with U: szczot3k and the newer key it closes the connection.
I've got access to SUL user:Szczot3k.

~ >>> ssh szczot3k@bastion.wmflabs.org                                                                                                                                
Enter passphrase for key '/home/fkszczot/.ssh/bastion.wmf': 
Connection closed by 185.15.56.13 port 22
~ >>> ssh Szczot3k@bastion.wmflabs.org                                                                                                                           [255]
Enter passphrase for key '/home/fkszczot/.ssh/bastion.wmf': 
Szczot3k@bastion.wmflabs.org: Permission denied (publickey).

You are attempting to ssh into bastion.wmflabs.org. The szczot3k user does not have access to this server because it is not a member of the "bastion" Cloud VPS project. I can see auth.log records showing that the ssh key exchange succeeded but then the group membership test failed causing the ssh connection to be closed: "sshd[3425]: fatal: Access denied for user szczot3k by PAM account configuration [preauth]".

The account does have access to the login.toolforge.org bastion via its membership in the Toolforge project.

I've used login.toolforge.org bastion to verify that I've got the access to my private key - tools-sgebastion-07.tools.eqiad.wmflabs:/home/szczot3k/2fa-reset-request.txt