Where did the notification come from? Is it from Dell's Asisstant app? If so, it is completely fine to go ahead and install.
Before you update , I would like to ask a few questions -
Does your computer come with Windows 11 already preinstalled?
You can type cmd in the search on the taskbar, make sure you use "run as administrator" to launch Command Prompt, then run this command: :
manage-bde -status
And share a screenshot please, I want to see if you need to suspend bitlocker first.