It is possible for a program to drop support in a specific version of a distribution? Comparing Windows 7 and Ubuntu 7.10

The context is that I found out that Firefox stopped supporting MacOS Mojave and Sierra, and it seems to me that not long ago Google stopped supporting Chrome on Windows 7.

What mainly intrigues me is that they stop supporting specific versions of an operating system, and from what I understand, Windows 10 is nothing more than Windows 7 with another skin and improved (or worsened, depending on each person’s perspective), among many more things that I will not mention, but you get my point.

That said, I know that my example is a bit exaggerated but it is a point of comparison that seems appropriate to understand my question.

Windows and MacOS release a “new OS” every few years, and Ubuntu, for example, releases a new version every year but it’s not necessarily a new OS, and also, when I go to install Firefox (or any other program) the normal thing is that I simply download an .deb, they don’t make me choose between different .deb depending on the edition or version of Ubuntu I have installed.

Even so, there are programs like AppImageLauncher that have different .deb files depending on the version of Ubuntu that is installed, including Bionic and Xenial.

From my absolute ignorance, a .deb is a .deb, just like an .exe is an .exe, but for example Mozilla can announce that it will discontinue the version of Firefox from Ubuntu 16.04 LTS backwards?