Something happened with the frame rate of terminal emulators lately. It looks like there’s a trend to run at a high framerate now? I’m not sure exactly. This can be seen in VTE-based terminals like my xiate or XTerm on Wayland. foot and st, on the other hand, are fine.
My shell prompt and cursor look like this:
$ █
When I keep Enter pressed, I expect to see several lines like so:
$
$
$
$
$
$
$ █
With the affected terminal emulators, the lines actually show up in the following sequence. First, we have the original line:
$ █
Pressing Enter yields this as the next frame:
$
█
And then eventually this:
$
$ █
In other words, you can see the cursor jumping around very quickly, all the time.
Another example: Vim actually shows which key you just pressed in the bottom right corner. Keeping j pressed to scroll through a file means I get to see a j flashing rapidly now.
(I have no idea yet, why exactly XTerm in X11 is fine but flickering in Wayland.)