I was surprised to see this extreme usage of Find My data. It must have happened in the last few days. The reporting period was roughly 60 days. When I reset it Find My used another 16 MB in 30 minutes without WiFi. That seems to be a lot.
Only change was to add a single shared AirTag. And that does not even update reliably.
Definitely odd. For me, it’s used 85.1MB since March, out of 225GB total data used.