Minecraft 19w07a, Minecraft 19w08a, Minecraft 19w08b, Minecraft 19w09a
On any settings screen that contains a slider, clicking it will enable the 'click' sound to play anywhere you click on the screen, not only inside the slider's area. This includes: the main Settings screen (with the FOV slider), Controls, Video Settings, Chat Settings, Music & Sound. Leaving the screen and going back seems to reset this behavior until you click a slider again.
I found this bug while testing
MC-144080. I left a comment pointing out that this behavior also happened, in addition to what was reported there, but since the reported behavior got fixed in 19w08a and this one still remained, I decided to open a separate bug report for it.
(May also be related to