Had a similar issue with tlp recently. I just happened to notice the laptop battery was at 100%, and said it was charging. I double and triple checked the config file, but the tlp-stat -b still showed the thresholds at 90%-100%.
Turns out tlp, at some point, started ignoring /etc/tlp.conf, and was pointing to /etc/default/tlp
That’s a shame, I actually enjoyed the first season