Hello I'm having the exact same issue on a ThinkPad T480 : running Bullseye, worked before and no longer since this summer (I assume this might be related to the bunch of updates that followed BootHole).
- Bug#968997: fwupdmgr: "Successfully" updates BIOS ... Lee Garrett
- Bug#968997: fwupdmgr: "Successfully" updates ... Hervé Werner
- Bug#968997: fwupdmgr: "Successfully" updates ... Lee Garrett