[p49k]

For a long time, in some browsers/OSes there was a bug (or perhaps an archaic feature that was accidentally triggered) where the cursor in an input could get stuck and cause all new characters to be inserted to the left; I'm assuming it's related to that.

[Jenk]

Notably this was a bug on the input for _setting_ your password, so if you think you've set Password123, you might have actually set 321drowassP, so even after fixing the bug it would still bite many users.

[Aachen]

This is the first I've heard of it, and as a Linux user I feel like it's the kind of thing I'd either know about or experienced first-hand. What kind of system would do that? And "for a long time", like, you can't ever login anywhere, it's kind of obvious and breaking functionality badly, how can this exist for more than a single release if at all?

[p49k]

To be clear, it’s intermittent. Perhaps one in 500 times an input is focused, it exhibits this behavior.

I have experienced this so many times over my life with so many different hardware/software configurations, and I have to assume others have as well. It hasn’t happened in years but could explain why the “fix” described in the parent post was implemented.