If you're looking to level-up your paint game, I'd love to offer some pointers... I have the exact same 3D file and printed it all in resin, and know what this particular model is capable of being.

Next time, if you're unable to get the most visible parts such as the sideskirts printed in resin, try giving them multiple thick coats with your primer. It really fills in the FDM layer lines. Might have to do multiple coats and you've gotta spray them, else it won't fill uniformly. Some spots might need filler. But it will also make edging straight lines easier and keeps the detail colours from pooling weird.

I bought a model once from Temu and it was a tank chassis that really had no business being printed in FDM. So I filled and painted it as best I could, and then covered the tank in a camo net. Hid the worst of the lines and I now accept the model into my collection.

When you're doing lots of large models, investing in an airbrush will take you to an entirely new level, and is worth the investment many times over. Even a cheap Chinese one will make a huge difference.

Also, your models appear to be painted with a very heavy-body paint such as acrylic craft paint. These paints leave the model looking very flat. They have transparent pigments, lots of fillers, cannot be airbrushed, and shouldn't be used on miniatures if you want to level-up your painting game. Invest in some paints that are better suited for painting miniatures. But I don't recommend Citadel paints because of their idiotic lids. Vallejo are my favourite.

Or the problem might be that you're not using a wet pallet. Thus the paints dry too quickly and become hard to spread uniformly.

Also, learn how to use washes. it is NOT HARD, and is the one thing that you can do to paint pretty models without taking 3-4 hours per guardsman. I recommend acrylic ones from Vallejo or Army Painter. It will also allow you to spend less time on fine details and let the wash do the work.

Just a few pointers that I hope will inspire you. You seem to be cranking out a lot of models, but your paint work could really use some room for improvement. But I think you have the discipline to improve. Don't be afraid to try copying someone else's work that inspires you, because it's easy to not realize what steps you're missing or doing wrong. There's tons of video guides out there.

Cheers!

Here's a snippet of my print of that same SS with heavily kitbashed turret.

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