From Microsoft:
Important: Certain cloud-based services in Office Lens for Windows, such as saving your pictures to OneDrive, OneNote, Word, PowerPoint, or PDF, will become unavailable after December 31, 2020. You can continue to use other features of the app as installed on your device. In addition, Office Lens for Windows 10 will no longer be available for download from the Microsoft Store as of January 1, 2021. To continue to enjoy all Office Lens features, we recommend downloading and using the latest version of Office Lens for iOS or Office Lens for Android on your mobile device.
As a refresher, Office Lens UWP is a camera-based application for snapping documents, auto-cropping and fixing skew errors, then uploading to OneDrive, where server-side converters would leap in to convert the image in various ways, including OCR into Word or Excel. All very clever, but Microsoft has gone in a different direction for next year. Which is a shame, since I used Office Lens as an OCR solution many times over the years and it worked pretty well.
But at least this latest stoppage isn't just for ye olde Windows 10 Mobile, it's a wholesale change in the way Office Lens is available. Incidentally, it's impossible to verify how much is local and how much is server side with Office Lens for iOS or Android - I guess we'll find out in 2021 when the old servers are turned off. It's likely that even the two download links above won't work in time, since Office Lens, as the name has suggested all along, is now firmly part of Office for the two mobile platforms, front and centre in the interface. So who needs external applications?