Information

Minecraft version: 1.21.1
Modloader: NeoForge
Forge version: 21.1.172
Environment: Singleplayer

First mod name: Elytra Slot
First mod version: 9.0.2

Second mod name: Easy Elytra Takeoff
Second mod version: 4.5

Description

When attempting to ground firework launch with the Elytra in the Curios back slot; fireworks instead launch as in vanilla. Moving the Elytra to the chest slot changes behavior to expected for Easy Elytra Takeoff.
Initially I thought this was a conflict with Flight Assistant or Do a Barrel Roll, but a new instance with only Elytra Slot and Easy Elytra Takeoff had the same problem.

Crash report

Not applicable.