NPM supplied password is incorrect when suppied on Win10 PC

I am running NPM Plug in (version 7.5.3.77) on FireFox (version 106.0.5 (64-bit)) on Win10. The Pinterest login using my own email credentials does not work. I allow NPM to autofill the login, and Pinterest does not accept the password.

Pinterest: "The password you entered is incorrect. Try again or Reset your password"

When I allow NPM to autofill on the Pinterest app on IOS 15, it works correctly.

So, I started experimenting. I tried copying the exact password information from the Vault and pasting it in to Pinterest, and it works correctly. But not if it autofills. (I counted the exact number of characters in the Vault password and it matches the count in the Autofill password, so I assume they are identical). I also found that if I allow NPM to autofill, then delete the last character of the password, and then retype that character, the login works correctly.

Not sure what is happening here. This serves as a workaround, but why have a password manager that requires you to remember the password in order to execute this hack?

Anybody else seeing this kind of behavior?

Thanks!