On background check
How strict is background check? Can I choose not to tell a short duration at a firm? (less than 2 months)
Your days of working with the cartel will come to light
Most background checks focus on verifying what you've said is true or false, not exhaustively uncovering everything you failed to say or didn't talk about. If you don't make an assertion about something and it isn't publicly available information, you're generally not going to be found out.
That’s not great advise. If the short stint shows up in your ADP etc records it’s easily found and will appear as dishonesty
Disclose it.
disclose it and interviewer will be interested in why I leave
Well they’ll likely find out either way. Would you rather control the message, or have the offer rescinded?
Disclose it. If you are working for a big company - the background check is automated and managed by someone in a Recruiting Ops team. The only time a background check is looked at is if it gets flagged for discrepancies or things like convictions. Be prepared if they ask what happened with a good rationale.
at the interview stage? I don’t have a good reason if interviewer asks about it
Not at the interview stage. After you get offer and I would just put on the background check document. If they ask why not on resume or LinkedIn, you can honestly say you did not think it was relevant to bring up. I repeat you should have some sort of good answer for why (in the off chance they ask), or you will get red flag on you potentially doing again.
Just disclose it. Don’t start a new relationship with a lie.