I have added a third-party extension for XML sitemap. When I generate a sitemap, I am getting "Service Unavailable The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later.". That extension company said, sitemap generation error is related to your server:
"libpng warning: Interlace handling should be turned on when using png_read_image"
I googled it found this solution for removing interlacing from the PNG files is using ImageMagick's 'convert' utility:
$ convert in.png -interlace none out.png
but I don't know how to apply it in Magento 2 for all images. any help would be appreciated