Keyboard laggy for a few seconds after using xdotool

If I use xdotool type "echo test string", whether directly in the terminal or through some other program, my keyboard is a bit laggy for two–three seconds afterwards. Why is this? Can I avoid it? (It also happens if I do complicated things like xdotool getwindowfocus windowfocus --sync type --clearmodifiers "echo test string".)

I don't know if xdotool is the culprit or there's something deeper, since I think some other situations also cause this lag, but this is at least a completely reproducible situation. I just don't know where to go from here in finding out what's happening :)

It also affects mouse clicks, not just typed characters. It's as if all input events are captured/ignored for a bit. In the video below, I start clicking on the other terminal right after hitting enter in the first terminal, clicking again and again until I see an effect:

This is a Thinkpad X270 with Xubuntu 20.04.4.

EDIT: Maybe I'm seeing https://github.com/jordansissel/xdotool/issues/367