Additions (1.21.5 only):

• Spawn eggs interaction

• Adding Grumm, Dinnerbone and jeb_ to spawn eggs will now flip them.
• Setting the variant block_state to "warm" or "cold" will reflect its change on cow, pig and chicken spawn eggs.
• Setting the Color (Uppercase C) block_state to the color strings or a number between 0-15 will also reflect on the sheep spawn egg

• Leaves

If you want the new stuff in 1.21.4 you can change the pack.mcmeta to lower the bounds of the addition to the main version.

!v1.6