Graph image download icon bug on iOS

[FloraDeath]

Describe the bug
When you click on the 'download plot as png' camera icon on mobile, it doesn't work. Seems just to affect iOS. We found the problem on a couple of iOS devices. It worked fine on Samsung Galaxy.

The error behaves slightly differently in different browsers.

Safari gives this error message:

Firefox and Chrome start to download it but the download fails:

To Reproduce
Steps to reproduce the behaviour:

1. On iOS mobile, go to any graph on a topic page, e.g. 'Tests', 'Virus tests conducted'
2. Click on the camera icon, 'download plot as png'
3. See error

Expected behaviour
Expect this icon to operate as it does on desktop. Click on image and it opens an export window.

Smartphone (please complete the following information):

• Device: iPhone XR and iPhoneX
• OS: iOS14.4.2
• Browser: Safari, Chrome, Firefox - see above for details

[archmoj]

This might be fixed in plotly.js v2.3.1.