Just got a Prime yesterday. First headache was that my prior Toyota account wasn't working: I tried to sign in but it said my password was incorrect (even though it was saved in my password manager). Even after resetting the account password, it would give the same error WITH THE NEW PASSWORD. So I created a new account using Apple signin (where Apple generates a munged email account and forwards it to my AppleID account. Finally was able to signin with the app. It scanned my VIN just fine and gave me the connect screen for the QR code. I went to my profile on the Prime's screen, got the QR code and... the Toyota app simple doesn't see it. It's scanning with the camera--which worked just fine for the VIN--but no matter how I hold it, it doesn't see anything. There's no "take picture" button so I presume it's supposed to automatically recognize the QR code. I first did this last night, and when it didn't work I thought maybe it needed daylight (even thought he screen is bright) but still nothing today. I tried a manual login using the account email (an incredibly tedious process since the munged address is LONG and mixed letters/numbers), and the car's screen returned a popup saying ------------------------------------ App login required Toyota app email sign in required to continue. ------------------------------------ and gives me the damned QR code to scan again. Edit: thought I had a workaround, but just had another glitch. Tried again, and just got stuck at the QR code. But I switched to the Camera app, and when I aimed that at the code it quickly popped up a link button to Toyota. I clicked that and it switched back to the Toyota app, which seemed to recognize the QR code and prompted me to enter a PIN. I did, and it asked me to enter it again, accepted it and... nothing. No option to do anything else and it did nothing on its own; the only thing to click on was a back icon: < , and selecting that just brought me back to the damned useless QR code scanner.
Had the same/similar issue two days ago. Affected the Toyota App on my iPhone and the spouse's iPhone as well. When I used my Password Manager (1Password) to fill in my credentials I received the error on both devices. I as WAG I tried entering the password manually and it worked. It's as if the Toyota App doesn't like passwords being entered by copy/paste. ymmv I don't use the App much for the Prime any more. I mostly just check level of charge and miles to empty. Being my Prime is a 2018 a lot of features have been dropped from Remote Connect. I assume Safety Connect still works but hope I never need it. My Wife's 2021 Venza has more features on Remote connect but Remote and Safety Connect cost twice as much.
I have the password issue solved, but not the QR code. The Toyota app simply won't see the QR code on the Prius's screen.
In case this helps anyone else in the future: after the edit above (using the Camera app and it then getting stuck in the PIN phase) I deleted the Toyota app, downloaded it again, and signed back in, and the car was registered--no more QR codes or PINs. I don't know if deleting and reinstalling the app did it or if it was already fixed and I just needed to force-quit/relaunch it and sign in again.