The smirking emoji ? on Snapchat can have a variety of meanings depending on the context in which it is used. In general, it can be interpreted as a suggestive or playful expression, implying that the sender has a secret or is up to something mischievous.
On Snapchat specifically, the smirking emoji can also indicate that you are one of the other person's best friends, but they are not one of yours. This means that they frequently send you snaps, but you do not send them snaps as often in return.
If the emoji next to a Snapchat friend's name disappears, it means that you have lost the particular level of friendship with that person. For example, if the Yellow Heart emoji disappears, it means that you are no longer best friends on Snapchat.
This can happen for various reasons. For example, if you haven't sent snaps to that person for a while, or if they have stopped sending snaps to you, the emoji may disappear. Similarly, if you or the other person have been interacting more frequently with other Snapchat users, this may cause the emoji to disappear.
It's important to note that the disappearance of an emoji doesn't necessarily mean that your friendship with that person is over. You can still continue to send snaps and chat with them on the app.