Can't connect wife's new phone via mobile app

My wife got a replacement phone, Pixel 8 and I cannot get it to connect to HA via the mobile app.

I log in, set the device name, then get an error message: “The ‘Mobile App’ integration is required to use the app, but it is not available on your Home Assistant server. Please check your server configuration and try again.”

The mobile app integration is, and always has been installed and active, the mobile app on my phone works just fine, it worked in her last phone just fine, and I didn’t make any changes to my HA server.

Any deas of what to do to get this work?