I'm facing this same bug reported to Chromium here about a year ago. Basically, on some websites like Facebook or Medium typing and hitting backspace messes up with the Touch Bar switching between the text editor and normal mode (so it flickers which is disturbing). Please see the video attached that someone from the Chromium team took to see how it manifests.
Unfortunately, the Chromium team didn't take the initiative to fix this and it seems it is apparently an issue for just a fragment of Mac users – but a pesky bug indeed for me and some others.
Have you come across this? I wish the Edge team could take a look and fix this themselves. For some time, Opera as another Chromium-based browser fixed this but in a later release the bug reappeared.