The lowercase o with slash, or "ø", has an extra pixel on the bottom in the default font. This has been in the game ever since the default font was created.
MC-46258
"ø" Character Has an Extra Pixel
Resolved
Fixed
2
Confirmed
character, font, graphics, pixel
Minecraft 1.7.4, Minecraft 14w04b, Minecraft 14w05b, Minecraft 1.7.5, Minecraft 14w11b, ..., Minecraft 1.8, Minecraft 1.8.1, Minecraft 1.8.3, Minecraft 1.8.8, Minecraft 15w49b
Minecraft 16w02a
Retrieved
Probably some pixel they accidentally added to character. Not a game breaking bug, but still interesting.