Dressing Room > Edit Character > Body > Mouths > Under "Owned Mouths", the Open Smile selection is no longer listed.  Had used this selection since the purchase of the game back in 2020.  I noticed the change since the 1.19.20 update.

Update 01/14/23:

The option for the "Open Smile" can be seen in Minecraft.net as an available option in September 2019. (https://www.minecraft.net/fr-fr/article/character-creator-now-bedrock-beta)