OK, this error can occasionally occur for unrelated reasons. Please try a different website until you find one for which you are able to use the “Auto-fill and Save” function without error. Then report your observations (answers to my questions above) for that site.
Assuming that you find a website that started out with no number on the Bitwarden extension icon, but then showed a number 1 after you use the “Auto-fill and Save” method, what I want you to do is to re-open the details page for that vault item, where you should now see two entries labeled “Website” (as shown in the screen shot below):
Please click on the “Copy” icon (circled in orange in the screen shot above) for the two “Website” fields, one at a time, and paste the copied URL strings into your response.