I refuse to pay for additional services through Amazon, so I can't say if they work or not, but I have not seen others reporting issues, currently.
In theory, if Amazon content downloads, Paramount content should also download through Amazon. But again, it's just a theory.
Now, there have been a few sporadic reports of login issues. It might be because SF is using Chromium 131, and Chrome is now up to 136.
Stan001
I sometimes sub through Amazon as its easier and usually more reliable. Previously I was able to download from a provider via Amazon when their own website wasn't working correctly.
But as I've seen before, I've come back today , made no changes yet I've managed to log into Paramount + so I can make use of the 7 day free trial.