Mastodon.social seems to have changed the way photos are displayed. I used to be able see photos that took up the full width of the message window when I expanded it. Very useful, lots of nice detail. Now they're restricted to a portion of the available width. So this is just me posting a photo (which you can ignore and therefore has no alt text) to see what happens.

Nope. It's reduced in width once posted. What's going on?