Smooth End Flashes

This lightweight resource pack makes it so end flashes look smooth instead of the standard pixelated look.

Check the gallery tab to view the difference (compression butchered this comparison so you got to click the images!)

According to LowSkillCamper, a Mojang employee

It is intentionally pixelated at the same pixel size as the sun and the moon in Overworld [as they] have the same type of gradient around them.

So whether you like this resource pack or not is purely preference.