The Framework bios (at least recent ones, but not original, so maybe OP hasn't updated) allow for a setting that, if the power is plugged in continuously, it won't fully charge the battery, even if your normal power limit is 100%.
Here is a knowledgebase article that goes into the details:
Most likely called charge_control_end_threshold (only mention of the identifier you used is in thinkpad_acpi.c), and not available on nearly all hardware.
Here is a knowledgebase article that goes into the details:
https://knowledgebase.frame.work/en_us/framework-laptop-13-b...