Hi Will Roxby,
We are trying to reproduce the same issue at our end which we could see in the attached video. But we couldn’t reproduce it.
As of now, built-in support to run the Flutter web app in safari browser is not provided by Flutter framework. So we are running the flutter widget in the chrome in release mode and using its localhost link in safari for ensuring it. Could you please confirm whether you are deploying the sample in this way? If not, kindly share the details with us. This will help us to assist you in a better way by reproducing the exact same scenario which you are facing.
Please let us know if you need any further assistance in this.
Regards,
Praveen G.