This was uploaded from my Samsung S11 using Chrome (randomly selected pic) and the pic icon in Quick Reply. Could it be the size of the file you're trying to upload?
What is the file type? (ETA: .jpg, got it)
Is the image local on your computer/phone or are you trying to upload something directly from your mail app or is it out on the internet somewhere and you're wanting to load from a URL?
Nothing (literally Nothing) has changed on the site in many many months.