ios 18.0.1 converted all my png images in my photo library to jpg

After updating to iOS 18.0.1 all of my png images have converted to jpg and lost their transparent backgrounds - I rely on my images to do my work for posting to social media. I have tied work around. I have even reserved and resent - some will keep the transparent background but most don’t. I age. Tried texting to myself instead to no improvement. I have tried emailing to myself and no improvement. This is so frustrating I regret getting a new iPhone 16 pro max and updating my iOS.

the photos on my iPad have alarmed their png backgrounds and the new ones I have sent show up fine on my ipad but not on my phone. And please don’t tell me to use my iPad instead, that is not a solution.