Why emails from Photos app went thru w/ 14.x but aren't from 15.2?

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iPad Mini 5, iOS 15.2. Last week I installed 15.2, coming from the last 14.x. With 14.x, I sent a few photos frequently from the Photos app, using the email indicator. As soon as I went to 15.2, I use the indicator, fill in the addresses, but the photos never arrive. These are photos in the 200-800 KB range. I can send them as much larger attachments from my webmail program on the Mini, but not from Photos. What might be going on?