shady past

Translations
темное прошлое
Despite his shady past, he managed to turn his life around.
Несмотря на свое темное прошлое, он сумел изменить свою жизнь к лучшему.
Definitions
A 'shady past' refers to a history or background that is questionable, suspicious, or morally ambiguous, often involving illegal or unethical activities.