I just opened a brand new Ryzen 2700X and the bottom of the cooler has the following:
1. Debris in the thermal paste.
2. Ridges in the thermal paste.
3. Dark marks/scratches on the copper heat surface.
4. Gaps with black material between the heat pipes on the bottom.
I don't know if that is normal or not. Based on some of the pictures I've seen the thermal compound should be smooth and the copper should be shiny with no gaps. Did I get a bad unit? I can provide pictures if required.
Open an Online AMD Warranty Request and show them the photos and see if it needs to be replaced under Warranty from here: AMD Warranty Request Form | AMD
From what you mentioned, it would seem like the Cooler will not cool the CPU very well due to poor contact between the CPU and Cooler.
Have you tried to clean off both surfaces of the CPU and CPU Cooler with Isopropyl Alcohol and then reapply a very thin layer of Thermal paste to see if it keeps the CPU Cool?