nice one, are your graphic card's drivers up to date ? it looks like a part of your display is just garbage data, if those are up to date, try fiddling with the display options, for science.
Old bug : The helmet of grit has never worked properly. It will give the wearer an extra bonus action if it goes below 50% health and will not take it away even if the wearer is fully healed.
this might be an actual bug, the data says it shouldn't stay once healed. I had a similar issue with temp HP that did not disappeared when reaching 0 but I don't have enough data on how and why to reproduce it reliably.
