Hercules Prima 5 with broken pistons?

Hello, I bought a Hercules Prima 5 a while ago and bought various new parts. I also replaced the carburetor. But after a while the moped didn't have much power. After that I bought a new air filter because the old one no longer had a seal. After a short while the exhaust started misfiring and I noticed that the exhaust was blocked and then I replaced it. When I test drove the moped I noticed that it still didn't have any power. I was only getting along at 15-20 km/h. Then I took the cylinder off and saw that the piston had a black layer of soot on the front and there was also black-brown combustion on the side under the piston ring. My question is, is it just the worn piston rings? Could someone tell me what else it could be because I don't want the same thing to happen again after 10 kilometers if I order a new piston and piston rings now.