Hi,
I've received a response from our development team:
Unfortunately, you cannot stop updating process. The only workaround is to not restart the browser when it prompts that a new update is available for you. Also, we don’t fully support versions before Mojave, Catalina and Big Sur. When users are running macOS Sierra version 10.12.6, our browser doesn’t have the necessary rights to update for such an old version, as CatalinaOS changed a lot since February 2020.
Thank you for understanding.
Sandu