I could not agree more.

The Linux version was really badly maintained for ages.

Circa 2014, I had to do weird stuff like sed on the .so flash plugin to bump artificially its version string from 11 to 12

This was to work around a requirement for VMware VCenter UI which required flash versions newer that the one available for Firefox at that time (11.2 IIRC).

I hope that at some points, Adobe will release the Flash source code. It's probably not the most beautiful code in the world, but at least, it would provide a reference implementation and help other implementations a lot.