In case of conflict of conscience/taste of that sort, resignation is the proper action and finding a job that better aligns with one's values. If you suspect legal violations, you can also file a police report.
Why not act according to your conscience and get fired if your employer really feels like it ?
Otherwise, in many circumstances a simple "is this legal?" question in a chat or chain of emails that I'll be there in case of discovery will have tremendous effects on whether some dubious thing is done willy nilly.
