The server is proprietary and last I checked you can't even turn off auto-updating or verify the binaries they push to you.
https://www.zdnet.com/article/linux-mint-dumps-ubuntu-snap/
In the Ubuntu 20.04 package base, the Chromium package is indeed empty and acting, without your consent, as a backdoor by connecting your computer to the Ubuntu Store. Applications in this store cannot be patched, or pinned. You can't audit them, hold them, modify them, or even point Snap to a different store. You've as much empowerment with this as if you were using proprietary software, i.e. none. This is in effect similar to a commercial proprietary solution, but with two major differences: It runs as root, and it installs itself without asking you.