Shulker boxes loose content after opening with Quick Right-Click - 1.21.4

[Silenc42]

Information

Minecraft version: 1.21.4
Modloader: Fabric
Fabric loader version: 0.16.9
Environment: Multiplayer, server

Mod name: Quick Right-Click
Mod version: 1.5

Description

I opened a shulker box using quick right-click from the hotbar. The shulker has items in it (no matter if already in there, opr inserted now)
I closed the shulker box
The shulker box is empty; all items are gone. No matter if the box is opened vie quick right-click or directly

I tried a few times, this was 100% reproducable.

I don't think this is due to interactions with other mods, but did not exclude the possibility.