After creating a fresh installation of Ubuntu 24.04, I installed DEB Firefox from APT by following Mozilla’s instructions from here. But I noticed that it was secretly replaced with Snap Firefox. I was able to verify this by checking the About Firefox page. This is the third time I noticed this.
It’s more than that. Ubuntu copies the Debian repos and then applies their own changes on top. Debian has a native (DEB) Firefox package, so Ubuntu specifically has to remove it for every new version.