The bug
In creative inventory, when searching for an item and then clicking the item to drag it to hotbar, the search term turns blue (see the screenshot attached). Similar to MC-123070, but in this case the search term turns blue like a link, which, I guess, is not intended.
Seems intentional. It's blue because it's highlighted (can get same effect highlighting text manually), and it's highlighted so that whatever you type next will replace that text.