javascript - How to deal with errors when doing canvas.toDataUrl() on safari and ios?

Question

First I installed two pictures in a p: the picture in base64 format and the local picture obtained by input type=file

Then use html2canvas to synthesize a canvas

Finally, in order to facilitate the long press to save the image on the phone, I want to convert the canvas synthesized by html2canvas into base64 using toDataUrl and then display it with the img tag.

But! Here comes the problem. I reported this error in Safari, and it cannot be converted to base64 on the phone.
All my pictures are in base64 format, and they are not cross-domain. There is no problem in Chrome . Does anyone know what happened? Please give me the ending