dnd 5e: What happens when a protection glyph is activated with Blink?

Flicker it would affect the creature that shot it

Glyph of custody He says:

When the glyph is activated, the stored spell is cast. If the spell has a target, it targets the creature that fired the glyph.

As flicker has a goal, the creature that activates the glyph would become the target of the spell. So this would imply that # 1 or # 3 are correct except for …

Flicker does not allow you to teleport to a location when you shoot

Flicker, in a roll of 11 or more, transports a creature to the Ethereal Plane. It does not allow any creature to teleport to any predetermined location of its choice (or that of any other creature).one The location of the creature in the ethereal plane depends only on where they were on the material plane. Therefore, none of your options is correct.

The real answer is:

4. The creature that fires the glyph is transported to the etheric plane at the end of its turn if they take an 11 or more.

1 – It is worth noting that at the beginning of each of your turns that begins on the ethereal plane, the creature will flash again on the material plane in a place 10 feet away from the one it left on the last turn. While not technically teleported, this would be the creature that triggered the choice of the glyph.