When a user updates their inventory, other players are seeing a popup message stating they lack permission to update Actor.
Tonight I had four players. For the logs shown here, one user added an inventory item from the compendium. They did not see any error. The other three players all saw an error at the same instant.
{"level":"error","timestamp":"2021-01-03 21:28:22","message":"User Mazi lacks permission to update Actor CyUMiEErdVy1M49k","stack":"Error: User Mazi lacks permission to update Actor CyUMiEErdVy1M49k\n at Function._onUpdate (/var/games/FoundryVTT/foundrycore/resources/app/dist/database/odm/document.js:1:8099)\n at async Socket.handleEvent (/var/games/FoundryVTT/foundrycore/resources/app/dist/sockets.js:1:2262)"}
{"level":"error","timestamp":"2021-01-03 21:28:22","message":"User Tuesday lacks permission to update Actor CyUMiEErdVy1M49k","stack":"Error: User Tuesday lacks permission to update Actor CyUMiEErdVy1M49k\n at Function._onUpdate (/var/games/FoundryVTT/foundrycore/resources/app/dist/database/odm/document.js:1:8099)\n at async Socket.handleEvent (/var/games/FoundryVTT/foundrycore/resources/app/dist/sockets.js:1:2262)"}
{"level":"error","timestamp":"2021-01-03 21:28:22","message":"User Broche lacks permission to update Actor CyUMiEErdVy1M49k","stack":"Error: User Broche lacks permission to update Actor CyUMiEErdVy1M49k\n at Function._onUpdate (/var/games/FoundryVTT/foundrycore/resources/app/dist/database/odm/document.js:1:8099)\n at async Socket.handleEvent (/var/games/FoundryVTT/foundrycore/resources/app/dist/sockets.js:1:2262)"}
Disabling VariantEncumbrance plugin stops the error messages so I believe the problem lies here.
This has been reported by myself, Ravenknight and others in the FoundryVTT Discord.