This isn't a new design. I don't think any of them are -- these are all 5e designs that date from Fizban's. It's just new artwork with the same design. Pushing into the controversy to tackle the wings and try and make sense of them might be the best solution here for Palmer.
Here's the topaz dragon from Fizban's:
View attachment 414005
The description in Fizban's states:
"their wings are shaped to propel them through both air and water." Which....I dunno, Palmer's wings seem sturdy enough to do that. The ones above seem more diaphanous and decorative, hahaha. Wings in nature aren't built for both mediums as far as I know (penguins don't fly, and most birds that dive fold their wings in when they plunge).
I like RJ Palmer's artwork better than this. The above ain't bad by any stretch, but RJ's feels so substantial and powerful. The dude above is more sleek and ethereal.
For comparison to other works, here's 2e's Topaz Dragon:
View attachment 414008
And 3e's design:
View attachment 414009
I think I like 5e's design the best out of the bunch. 3e's is OK, and fits with the other "made of gem" designs in 3e, but it looks a little...melted...and very chaotic (which is apt, I suppose!). 2e's looks pretty "dinosaur"-y. Intimidating, but it looks like it'd be a bit lumbering and awkward.
I'd say RJ Palmer's is the best illo of a topaz dragon yet! I'm sure he was working within the design constraints the team gave him, which includes the backwards wing design.
I imagine these wings "flap" like a hand grabs. The topaz dragon is grabbing fistfuls of air or water and hurling them back and beneath to push off.
.....yeah, still a strange deisgn.
It's weird, and I like that they got weird with it. Not super successful, I guess, but I appreciate the experimental attempt.