This is affecting our users in production. Can somebody help?
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Where are you located and where are your servers that are making requests? 
If you try it now does it work?
We figured it out. Apparently, this wasn’t working because we were using the image URL as the image name when creating the image in our code. This method had been working for years, but it suddenly failed. We made a change to use a random image name like image1.png, and it seems to be working now. However, it’s very odd that we were getting a 403 error with a blocked response for issues like this. Anyway, it’s working now. Thanks!
I’m glad that you found a fix with the name.