Incredibly large Docker.raw file on fresh install

Definitely not normal behavior and you could report it as a bug, but the distribution you are using is not supported officially. I understand that Linux Mint is baded on Ubuntu, but Ubuntu is also based on Debian and both has separate installation instructions.

If you can try Docker Desktop on any supported distribution and still experience the same issue, you could report it on GitHub, which you did

But you left out that it was installed on Linux Mint.

We also had a similar report recently

also on Linux Mint