I have tried rigoursly to find a stable way to trigger it, without any luck. The bug is common for Lineage 18 and 19 as well as AICP R
Unfortunately we do not have an Android 11 for the Pro1, so we can not tell if the bug is in Lineage or deeper.
When the bug kicks in, the phone DO draw power from the charger, but only to sustain what ever the phone is doing, not to charge it, so the battery percentage remains at a (roughly) constant level for hours.
There seem to be some system to prevent over-charging a constantly connected phone, my personal theory is that it is this system,