This is something I've noticed since 1.20.30 but for some reason, keystrokes can get delayed, held, or ignored at any given time. Sometimes when I press W to walk and press space to jump while sprinting, the game will hold these keys for a random amount of time. Note that this does NOT affect mouse movements, I've seen nothing like this happen with mouse inputs, only keystrokes.
Sometimes it mainly happens with a large load on my system (either from the game or something else in the background while I'm running the game, Like RYMcast to play music in the background), this also happens with no background apps open and lowest graphics settings. This also ONLY happens with Minecraft, no other app gets this problem, so I'd assume it's a Minecraft issue. So far this makes Minecraft pretty unpredictable and annoying to control when it comes to randomly holding or ignoring keystrokes and sadly it's gotten me killed in some survival worlds.