Completion broken… Hum, looks like the shift key is cheating on me:
Typing "Op<TAB>" in xev(1) shows:
It turns out the shift key is a bit sticky and does not raise completely as soon as I release it. When I press Tab and it is only half-raised, the #typematrix skin deformation is strong enough to press-down the Shift key again and the keybaord sens a Shift before the Tab key is down.
This stuck key (along with the Ctrl key just bellow which is also sticky) also explain how I managed to incidentally open a lot of different Firefox windows when writing comments without being able to reproduce it: Ctrl + i ≠ Ctrl + Maj + i.
The social network of the future: No ads, no corporate surveillance, ethical design, and decentralization! Own your data with Mastodon!