External sharing - forcing to sign in, instead of verification code

Recently i've migrated sharepoint site from one tenant to another. In the old one when someone shared a folder externally, the recepient was able to authenticate via verification code, that was sent to the same email adress. In the new tenant sharepoint requires sign in, but the guest accounts are not created, when creating external link (can access the folder in the old tenant without guest account).

Sharing polcies are the same (admin centre and site: New and existing guests; verification code reauthenticate after 180 days)

Any ideas what i'm missing?

Thank you.

Jan