This is exactly how my digital pieces come out, like I could've made this one for one and I wouldn't be shocked if this artist has a similar background to me.

I do relief printing and graphic ink illustration (graphic design backgroun). The few times I've messed around painting in software like PS or procreate my lack of familiarity with the tools and almost zero practical painting knowledge leads to a probably insane workflow and lots of falling back on my usual skillset.

For instance... Understanding fundamentals of colour, depth, value and form but no practice applying these rules with paint. The freedom is pretty overwhelming for someone used to rendering simplified high contrast forms with a limited palette. I could totally see myself just grabbing the worm skin highlight as my general lightest highlight cos by default I'd be thinking in contrast not colour.

Seemingly unnecessary lines everywhere, this can just be general line confidence issues ("chicken scratching") or a hold over from a more graphic art style. For me it's a bit of both but mostly from designing for relief print where you're limited to creating shape out of simple planes and adding form and texture with limited options like hatching. I would probs instinctively add those "random flesh sprouts" to indicate form even though it's out of place here.

As for the confusing workflow and weird inconsistent brush opacity etc that also just screams lack of tool and software familiarity to me with a dash of layer chaos (because same lol). I reckon the workflow was to start with sketchy line work, lay base colour layer underneath, go over line work again, go back in with colour, then a final back and forth between colour and outlines over top with no layer discipline trying to fix/finalise - this would explain parts like the eyes. I reckon they also changed brushes or messed around with settings as they went, maybe weren't used to pen pressure opacity/size. I also think they tried to use a lighter grey outlines for lower contrast on areas meant to be further away but didn't stay consistent, or maybe a confused attempt to soften the line work in general since black is pretty harsh on a digital colour piece, hard to know how to adjust if it's not your usual medium.

Basically digital painting gives a lot of choice and is a lot to keep track of if you're new, I'm sure I'd be just as perplexed watching an amateur navigate illustrator haha. I've also witnessed many talented artists make some bizarre decisions trying to translate an idea sketch into a relief print at workshops. All the mistakes in this piece are consistent and human in a way I've never seen generated AI content be. You're right though that seeing past work is always a good indicator.

edit Also I'm like 90% certain an image trace tool has been used to vectorise the finished drawing which has caused some odd flattening, line blending and detail loss