MacOS to me started to regress ~2012. I can’t remember what specific release it was, but one major MacOS release around then no longer remembered my MacBook’s external monitor layouts between work and home anymore and it was always “random”.

Spotlight, AirTunes/Airplay, iTunes, etc all also just slowly degraded. It’s like Steve Jobs was personally doing all QA and it just stopped when he died. I remember iTunes genius being SO GOOD that it cost me a fortune in song purchases, but now that apple just gets my monthly music payment, discovering new music is hard again.