WHY do old Apps keep Crashing on newer IOS

Why do old games crash on older operating systems? I think it’s because of The swift programming language changing after IOS 12 maybe some of the code turned into a different meaning and stuff so when the app tries to open it, it sees invalid code and crashes. Tell me if I’m wrong I tried it on my iPhone 6, and it worked perfectly. YouTube video of how the problem looks like. https://youtu.be/GBNcQHxGP2o?si=w9EG8_rdTtmKQyKp