The status bar is not continually updated. Just let it run. My Photos Library has also more than 50000 photos and videos and the scan for faces finished after three weeks.
Photos may have recognised many faces by now, but it will add only a person to the People album after it has recognised the same person in many photos, and only a small selection of the few most frequently recognised people. This will only happen, after most photos have been scanned.
You can check, if already some faces have been recognised, by enabling the option "View > Show Face Names" in the View menu in Photos. This way you will be seeing circles around detected faces and can already enter a name in the text field below the circle, to add the face to the People album.
One thing you could also do while waiting for the faces scan to finish - you may want to check, if your Photos Library is containing legacy media. Older versions of Photos allowed us to import photos and videos in formats, that can no longer be processed on macOS 11 Big Sur. A video or photo in format that Photos can no longer read can prevent Photos from analysing the library. Such items should have been removed and converted to a more compatible format while you still have been using a system version that has been supporting these formats. On Big Sur the safest format for videos is H.264 or HEVC, and for photos I am sticking with the RAW format of my main camera, TIFF, PNG, JPEG, and HEIC. This list for iMovie could give you an idea, which media formats you can still use with macOS 11 Big Sur: About incompatible media in iMovie for macOS - Apple Support
An easy way to search for legacy Media are smart albums, where we can search for the filename extension, also look at the status bar below the "All Photos" view. Are any items shown as "unable to upload to iCloud Photos Library"? About the status bar in Photos for macOS - Apple Support
