My 2017 MacBookPro laptop swings from 12GB free to 600MB free back to 12GB for no apparent reason, while giving me warning notifications of low disk space that

My 2017 MacBookPro laptop swings from 12GB free to 600MB free back to 12GB for no apparent reason, while giving me warning notifications of low disk space that I can't turn off. The only reason I have 12 GB free instead of 3-4 is that I uninstalled a whole bunch of stuff so that I could actually do a Time Machine backup. Yes, I had to uninstall stuff in order to do a backup. Seems backwards. These annoyances from the company that supposedly is obsessive about user experience make one feel helpless and frustrated. Overall, Mac feels less janky from a GUI/visual point of view than Linux, but frankly I'm spending more and more time on Linux because it's just more predictable. Also lots of Raspberry Pi tinkering. A rogue Windows update bricked my machine the day before an important deadline. This is just so unbelievably unacceptable that I can't believe we collectively put up with this nonsense. Yes, default macOS is more aesthetically pleasing than default Linux, but the helplessness when something goes wrong ...