I think you got it backwards.
Over the last 20 years, the SLD govt used to literally sell new legislation for bribes, PO (currently in charge of Poland) literally has right now a guy in their ranks who has likely stolen 100s of millions PLN from a public company, but is the prime minister’s BFF so the prosecutor canceled the investigation. The stuff PiS has done is nothing compared to those.
I actually think that the Anti- Corruption Bureau that PiS founded is one of the core reasons Poland was able to mostly weed out the post-Russian corruption (corruption is unfortunately the main export of Russian culture, every country they invaded ended up extremely corrupt).