Is this mix of SharkBites and PEX under my sink actually legit?

Seeing SharkBites used as a permanent transition from copper to PEX usally screams 'handyman' rather than 'professional plumber' to me. It is a common shortcut, especially with insurance subcontractors who are trying to burn trough a punch list as fast as possible. While those push-to-connect fittings are technically rated for permanent use under most modern codes, they are widely considered the 'lazy' way to handle a copper-to-PEX transition.

What stands out as a red flag is the mention of **expansion rings**. If the guy used those, it means he has a PEX-A expansion tool, wich is a specialized and somewhat expensive piece of equipment. If he had that tool on him, he absolutely shoud have used a proper copper-to-PEX adapter. Using a SharkBite when you acutally have the right tools for a mechanical connection is just cutting corners. It is like having a drill but deciding to hammer a screw in instead. The 'messy' look with the flex tubing usually happens when someone does not take the time to cut the PEX to the correct length or use support brackets. If those lines are just flopping around, they can vibrate against the cabinet or the drain pipe, which eventually leads to noise or even wear over time. You want your supply lines clipped and organized, especially the hot side going to the dishwasher.

Since this is an insurance repair, you have every right to be picky. If those fittings are going to be accessible under the sink, they will likely be fine, but they represent a lower standard of work. If any of those connections are going to be buried behind a wall or under the floor once the project is finished, I would demand they be replaced with soldered or pressed adapters. You do not want a cheap fitting failing inside a wall you just paid to have repaired.

I’m just starting to learn about this stuff for my own DIY projects, and that part about the lines vibrating realy caught my eye. If the pipes aren't clipped down, does that cause those loud banging noises whenever the faucet gets turned off? I think people call it water hammer.

Also, since you mentioned the expansion tool, is there a big difference between the PEX-A they used and the PEX-B you see at the hardware store? I’d be worried if the insurance guy just grabbed whatever was cheapest at the bottom of his van instead of using the right material for a long-term fix.

To answer that PEX question, PEX-A (the expansion stuff) is way more forgiving becuase it has 'shape memory'—if it kinks, you can actually fix it with a heat gun. PEX-B is stiffer and basically toast if it bends too far.

One thing to watch on that dishwasher tee is the material. If it's a plastic push-fit tee on the hot side, those get hammered by the high-temp cycles. I’ve seen the internal plastic components in those cheap fittings get brittle and fail way faster than brass. If it looks like a rat's nest now, those lines are definately going to rattle and cause issues down the road.