⇧⌘L to Toggle Flag does not work on my Mac. I’ve tried changing the shortcut to a couple of other combinations to no avail. I saw this post, but I’m actively in the Draft I want to Flag (cursor is blinking, and I can type text). Other shortcuts (e.g., ⇧⌘A to Archive) work fine. I’m running macOS 26.4 on a 2025 MBA and using version 51.0.2 (770).
Update I just tried on my 2024 Mac Mini running Tahoe 26.3.1 (a), also using using version 51.0.2 (770), and the keyboard shortcut works.