That change is hilarious. So many potentially goofy reasons for it happening but my best take is google deciding not to host any data it can’t mine or use. The privacy policy on location history was quite good and effectively granted users privacy.
If they cared about privacy they could have easily hosted the data encrypted with a key only known to the user rendering subpoenas useless for that service.
Or they could just not upload it. No one trusts E2EE systems; you can see Apple tries it and everyone just accuses them of putting secret backdoors in.