CoreMotion on my Apple Watch Series 9 is causing the battery to drain quickly

I have a (private) watchOS app that uses CoreMotion. This app has been fine for several years but in the last few months (after rebuilding the app) I have found that having the app sit in background doing nothing drains the battery at a rate of 6% or more per hour.

I have isolated the cause of this to CoreMotion. Even when none of CoreMotion's methods have been invoked (e.g. startDeviceMotionUpdates) the battery drain persists. It seems that merely linking to CoreMotion is responsible for the battery drain.

I have resorted to uninstalling the watch app (it is a companion to an iOS app) when I'm not using it since it is easy enough to reinstall it from the iPhone as required. However, this is a really strange problem. CoreMotion is not supposed to be powering any of the sensors if it's not detecting.

BTW I have background off for the watch app--no background refresh, no background location, etc. I'm also not using HKWorkoutSession.

I believe this problem was introduced in one of the watchOS updates in the last 6 months. Does anyone have similar issues with CoreMotion?

[Re-Titled by Moderator]