PNGs blurring in email campaigns

Have Squarespace changed anything regarding image sizes for PNGs in email campaigns recently?

I have an image (PNG file with transparent background) that I've created for the bottom of my email campaigns that shows my four latest Instagram posts. It's always uploaded clear but for some reason this time now that I've updated the image to show my new posts it's just loading blurred no matter what image size/dimensions I try. 

I've been reusing the same template when making new email campaigns so the original image stays clear, but when I try to reupload it it also blurs - so that leads me to think Squarespace has changed something on their end?

The original image that's showing up clear (unless I try to reupload it) is 7324 × 1712 and 16MB (which I know is wider than their recommended sizing).

If anyone has some info or knows a work around please let me know! I don't know how many hours I've spent trying to fix this.

8 hours ago, home165 said:

Have Squarespace changed anything regarding image sizes for PNGs in email campaigns recently?

Have you raised this with Squarespace Customer Care?

'Same here.  This is a new problem.  All png images put into email campaigns are blurry.  Size is large enough, 'not the issue.

This was not a problem before.