The headlining feature of Netherite items is that they do not burn in lava or fire.

However, the Netherite Glider still catches fire and becomes totally useless while in the nether - while I think that the idea of gliders being able to catch fire is interesting, (though i wish it could have a config option to turn it off) I don't think that it makes sense for my netherite glider to catch fire.

This sounds like you crafted a netherite glider and did not give it the nether upgrade?

That may be correct. It's difficult to tell how the upgrades work without tooltips, to be honest.

I feel the mod page covers everything but I’ll consider improving these tooltips for QOL in the new year

Its just weird that you have to craft it with netherite but it still needs to be upgraded to make it fireproof.

I think that the idea of the Nether upgrade is an interesting way to not gate gliding in the nether behind end-game gear, but I also think that a Netherite Glider should not be able to burn >.<

The upgrade should be used for every non netherite glider, meanwhile the netherite one just shouldn't be able to burn up.
There should be some consistency with how the vanilla lore/logic works.