'clear' is not an option when attempting to autocomplete the <effect> argument in /effect

If you type:

"/effect @p " (with the space after 'p')

and press tab, it will come up with "minecraft:".
Press tab again and it will come up "minecraft:strength" (or whatever effect) and in the chat will list all possible effects. Keep pressing tab to scroll through all the available effects, but "clear" will never show up.