Hello, I hope you are doing well.

While debugging a different mod, I looked through the log and noticed it's being spammed with the line
[modloading-worker-0/ERROR] [net.minecraft.entity.ai.attributes.GlobalEntityTypeAttributes/]: Entity dragonmounts:aether_dragon has no attributes
This doesn't limit itself only to the Aether dragon but every single one of them.
It's being spammed roughly 150+ times throughout the log, only at startup of the lancher and entering the world.
While playing however, I didn't see any issues with it or the dragons for that matter (yet.)

Nothing else is mentioned in the log file about errors regarding your mod or any other issues.
Just a spam of this line.
Any ideas if this is an issue that needs attention or..?

GlobalEntityAttributes is an outdated (and quite frankly, stupid) frantic feature that was implemented to fix the impossibility of having attributes on custom mobs back when mojang broke all that towards the end of 1.16's life.

Unfortunately, I do not support the 1.16 version of this mod anymore and since it isn't causing and major issues other than log spam, this will not be receiving any attention.
Sorry about that.