Because of various privacy legislation, and people not wanting Google to track them as much, they stopped syncing the data to Google servers. As someone who’s worked at big tech companies, my guess would be that storing so many people’s location history was flagged as an issue during a privacy audit.

It’s entirely local now. You can enable encrypted backups and back up the data, however you can really only have the data on one device now, and the web version is gone.

If you pay for a device, you should be able to do whatever you want with it. Apple having so much control over it means that you don’t fully own it.