What I noticed in all these cases is that we are talking about PNG images with almost 1MB, which for a PNG is very heavy and is not common. But on the other hand, it doesn't make sense that this happens, because if you upload the image again, it doesn't happen anymore.
So at this moment the suggestion I can give is that when you detect this situation, upload the image again.
These images are straight out of midjourney. Sincerely speaking, I have no time to convert those to other formats before uploading to talkimg.
And I don’t know if it is me only, but I don’t see the image you say you see. I am on safari mobile right now.