Using crossbow and skyglass at the same thing makes a wonky image.

Start a new world in minecraft java snapshot 21w10a.

2 or 3 items. its a crossbow, arrow, and spyglass.

Follow the steps.

Load Crossbow. Put Spyglass in offhand. Use Spyglass. Switch to crossbow from a empty slot.

Rotate the camera to point at you with F5 and see your self.