Just a simple shader to remove actionbar and title shadow
By setting the text color to #4e5c24
(78, 92, 36) the shadow of the text will no longer show.
This restores the behavior of old minecraft versions and allows you to, for example, create custom GUIs.
The text that is modified by this shader is text in the actionbar, subtitle, title, chat, advancement screen and in item names and lore.
A command could look like this:
title @s actionbar [{"text":"This text has shadow ","color":"white"},{"text":"but this text does not :D","color":"#4e5c24"}]
Feel free to take the shader files and drop them into your resource pack.
Credit is not needed but always appreciated.