Effective January 1, 2022, there will be no further updates for the OneDrive application on Windows 7, 8, and 8.1. In addition, files will stop syncing to the cloud on March 1, 2022.
Note, however, that files on those operating systems can continue to be added to OneDrive by manually uploading them. If you are unsure how to do this, see the first two examples in Upload photos and files to OneDrive.
As explained in Ankita Kirti's blog post, End of support for OneDrive desktop application on Windows 7, 8, and 8.1, the reason for this change is "to focus resources on new technologies and operating systems, and to provide users with the most up-to-date and secure experience".