It differs from language to language. Java was designed for "write once, run anywhere" - which includes in the future. They have been very careful -- too careful, some would argue -- to keep backwards compatibility. Other languages don't care about that so much, preferring evolving rapidly. Unfortunately, it's not something you can predict. Also, compilers change, sometimes introducing bugs of their own, sometimes fixing bugs that the software relied on. A program doesn't exist in a vacuum.

People have gotten used to the world moving under their feet. I got used to common lisp in the 90s, and it bothers me that some code I wrote in other languages doesn't run after 10 years. I even had things stop working during the same major version of python.

I find old Linux executables, and Python programs, are two particular cases where it's very hard to run old versions.

I keep a set of old Debian VMs around, to find a machine from the time a program was created, so I can run older stuff.

(If you wonder why I'm running so much old, unsupported stuff, that's academic research software for you)

That what you would think.

I started using again an old ~12 year old Asus Android tablet. Impossible to browse the web, as it doesn't support newer TLS versions, newer CA. Impossible to install more recent software on that old Android version. Play store don't even work anymore (probably for the TLS reason). Then I wanted to install a recent Linux, and even after working around all the above and have the Asus bootloader unlock app installed, with mitm proxy to simulate old TLS, I realized that the Asus service to unlock bootloader doesn't exist anymore...

Software rot so much faster than hardware sadly :( (the good news is that old software is also full of vuln, so I was able to install my Linux - postmarketos - anyway without unlocking the bootloader, and to my surprise, everything works perfectly out of the box)