Meredith Whittaker reaffirms that Signal would leave UK if forced by privacy bill::Meredith Whittaker, the president of the Signal Foundation, the organization that maintains the Signal messaging app, spoke about the U.K.'s controversial new privacy bill at TC Disrupt 2023.
https://signal.miraheze.org/wiki/Secure_Value_Recovery
The master key is stored. At the very least somebody with the master key could be able to engage your contacts, without getting a new key warning.
Per that link, the encrypted master key is stored.