Ah, I love it when people do OC redraws over the span of a few years / months. And don't worry, none of this here I'd classify as mature. I don't think anyone minds a few sexy bullmen and scalies now and again lol.
Your art is very symmetrical, is that a stylistic choice or are you using the flip horizontal tool? No judgement I do it too, aha, I'm just curious! Another thing I notice is that your art has very minimal shading. I think you should try to explore more dynamic shading / highlighting options, like you did in the Rose Quartz redraw!
You have a really charming art style. Its hard not to smile looking at it.
I do agree that you should explore some more dynamic shading though. It might be worth it to practice without using the flip too as it will give you greater freedom for posing your characters and sometimes things being too perfectly symmetrical can be a bit off-putting.
I love Greg the Quagsire. He looks like a lovable dork.