Minecraft Client 1.15.1 
Mods : No mods it is a vanilla client

Minecraft Server 1.15.1
Mods: No mods it is a vanilla server

Client-Side glitch

To recreate,

Step1: Place torch on leaves. (while shift and without shift both works)
Step 2: the torch is used up, the torch disappears and not returned to the user. 
Step 3: Disconnect and reconnect to get the used torches back into inventory slot .