The bug
Unlike other celestial bodies such as the sun and moon, stars do not appear to be tied to a texture file, and therefore cannot be modified via a resource pack.
How to fix
Introduce a texture file for stars.
Linked issues
relates to 24
MC-278413
Chat background cannot be retextured
Open
MC-268805
panorama_overlay.png no longer works
Resolved
MC-268927
The dark background in inventory screens cannot be changed via resource packs
Resolved
MC-269079
Death screen background cannot be retextured
Resolved
MC-269364
Sign editing screen can no longer be retextured
Resolved
19 more links
Can confirm.