Short answer
An invalid or expired QR/code often means the install code has already been used, or the eSIM is already installed on this or another device.
What to do first
Open the app → Settings → Get Link to Install eSIM.
If you see an error
Check whether the eSIM already appears in phone settings.
If you see an eSIM without a phone number, open its detailed settings. If it shows eSIM Go, this is likely our eSIM.
Contact support with:
screenshot of the QR/code error;
screenshot of the full SIM/eSIM list;
whether this is the same phone or a new phone.