Ubuntu 24.04 doesn't install .deb files by default
For years, Ubuntu has been promoting its ‘universal packaging format’ Snaps over ‘Universal Operating System’ Debian’s deb packages. It has gone to the next level in the recent release of Ubuntu 24.04 LTS. Actually, it started with the previous version Ubuntu 23.10. If you download a.deb package of a software, you cannot install it using the official graphical software center on Ubuntu anymore.
Source: I AM SO DISAPPOINTED WITH UBUNTU 24.04
If all else fails, there’s always Debian or other Ubuntu-based distributions.