I've seem some studies on salted pickles potentially being carcinogenic, specifically causing stomach cancer. This is due to pathogens, n-nitroso, or carcinogenic enzymes in the pickles. The most commonly cited one is kimchi. I don't think the science is final though, and I did see another study that claimed they were only dangerous for those with h. pylori infections, and another that the consumption needs to be high.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4316045/

https://www.buesingnaturopathic.com/fermented-vegetables-can...