According to the Device Care app, I've been on battery for 8 minutes this morning, only using Screen, Android System, and Chrome. 12% loss of battery in less than 10 minutes of only moderate usage.
The performance was awful, so I rebooted. That seems to have moderately stopped the battery bleed.
I'll try the cache wipe thing next before I set it reboot nightly, but this is really becoming a tiresome headache. I don't trust this device anymore.