Hubspot has enforced 2FA globally on all connected accounts.

If you have Hubspot connected & upload a CSV you may see an error as such.

This means any active Hubspot connection you have to your account needs re-authorization.

The solution for this is to disconnect and reconnect your Hubspot account from your Integrations tab.

As a result of doing this you may see some syncing interruptions, but once done - it should be stabilized.