For years, Intel's compiler, math library MKL and their profiler, VTune, really only worked well with their own CPUs. There was in fact code that decreased performance if it detected a non-Intel CPU in place:

https://www.agner.org/optimize/blog/read.php?i=49&v=f

That later became part of a larger lawsuit, but since Intel is not discriminating against AMD directly, but rather against all other non-Intel CPUs, the result of the lawsuit was underwhelming. In fact, it's still a problem today:

https://www.extremetech.com/computing/302650-how-to-bypass-matlab-cripple-amd-ryzen-threadripper-cpus

https://medium.com/codex/fixing-intel-compilers-unfair-cpu-dispatcher-part-1-2-4a4a367c8919

Given that the MKL is a widely used library, people also indirectly suffer from this if they buy an AMD CPU and utilize software that links against that library.

As someone working in low-level optimization, that was/is a shitty situation. I still bought an AMD CPU after the latest fiasco a couple of weeks ago.