Alt-Tab:
The last but one patch broke Alt-Tabbing again, after it was fixed a couple of patches after launch. Really inconsistent again now and frequently one has to use Ctrl-Alt-Delete instead.
Map vote:
No longer works at all for me since the last mini-patch.
F-key:
As others have reported, seems to have become inconsistent. Detection of people needing a resurrection when playing as medic has always been bad, but it seems to have got worse.
Engineer:
When one runs out of supplies as engineer, the game will constantly play the sound effect that is used when you try to use an ability when you’re out of supplies. It only stops when you are back to 1 full supply bar. Happens every single time. Has done so for at least 2 patches.