I still use Macs because data on a physical disk seems perfectly reliable, but I've been bitten by so many of these bugs in their apps. iCloud files completely disappear, then reappear a day later. Highlight a couple chapters of a PDF in Preview, then reopen the file and they're gone because iCloud thinks the older unhighlighted version is newer or something. Madness. I don't touch any of these Apple services/apps anymore.

There's very clearly a fundamental bug in whatever sync framework they seem to share across everything. It's bad enough to have data disappear entirely or deleted data reappear, but then when data shows up in the completely wrong place, and this has been happening for years and years and still isn't fixed... I don't know what to think.

You're right. There's no other word for it but "insane". They can engineer their A-series and M-series microchips, but it's been over a decade now and their sync is still fundamentally broken.