I can reproduce this for bangs that are 3 characters or more and at the end of a search query.
This can be annoying on mobile where keyboards try to be helpful with spaces around punctuation. When entering punctuation it moves the space from in front to behind ("text !" -> "text! "). That's well and good for regular texting, but without manual moving around of spaces typing "query !bang" results in "query! bang". So, I opt to move the ! to the end ("query bang!"), but as the screenshots show, this only works for one- or two-letter bangs.
To be clear: The screenshots were taken on desktop, but the behavior is the same on mobile
