Japanese maple... what's happening?

First time ever growing Japanese maples. They are both in pots and one seems to be doing well, the other not great, seems kind of anemic. Any idea what these leaves are telling me?

The last one is the healthy tree. Both seem to be getting the same amount of sun which is partial during the day
We live in an area near the beach that gets fog for half of the day.
Thanks in advance!

Are they the same cultivar?  Some cultivars take sun better than others, and I wonder if the leaf tips on the one are showing sun stress.  Is there any less of this effect on the branches that are entirely in shade?
I'm not sure beyond that.  It doesn't look like a fertilizer thing to me... but I'm not a JM expert, either.
Best of luck!

While it's hard to know for sure what happened, I've seen Japanese maples (and other plants) show similar damage if they get underwatered even once... Of if it was in a tray and sat in water.  Living in a small pot can be brutal. If it got watered a couple hours late one day and it went really dry you could get damage like that. I can't guarantee that's what it was but some sort of watering issue is my first guess.  If you're sure you've been keeping it evenly moist, not too wet not too dry, getting a little too much sun would be my second guess but you seem like you have a fairly mild climate compared to mine so that's why it's my second guess.

Ours get that during drought or flooding.  I would check for rootbound and drainage first since they are in pots.  Maples often have a deep tap root and get stressed if the pot gets too small.