This is continuation to the issue #329.
So as seen on screenshots, when using ImmediatelyFast and Legendary Tooltips + Equipment Compare comparison tooltip is blank.

LegendaryTooltips-1.21-fabric-1.4.11
EquipmentCompare-1.21-fabric-1.3.12
fabric-api-0.115.2+1.21.1
Iceberg-1.21.1-fabric-1.2.9.2
ImmediatelyFast-Fabric-1.6.2+1.21.1

Links:
Legendary Tooltips
Equipment Compare

Hey there, author of Equipment Compare/Legendary Tooltips here. I was directed to this issue from a user that is having the same issue with this combination of mods. I have narrowed the issue down to a problem in Iceberg's tooltip rendering that has subsequently been fixed. Version 1.2.14 1.3.0 is releasing soon that will include a fix for this problem. 😃