Privacy Implications of Accelerometer Data: A Review of Possible Inferences
source:
https://dl.acm.org/doi/pdf/10.1145/3309074.3309076
TL;DR:
They can be used to Track Location (even if GPS is disabled), uniquely identify who the user is and what Demographics they are part of (age, sex and more), Keystroke Logging, Daily routine, mood and even Personality Traits.
"Accelerometers are among the most widely used sensors in mobile devices, where they have a large variety of possible applications. They are commonly regarded as not privacy intrusive and therefore often less access-restricted than other sensors, such as cameras and microphones. However, based on existing literature, we found that accelerometer data can enable serious privacy intrusions by allowing inferences about a device holder’s location, identity, demographics, personality, health status, emotions, activities and body features."