Just look at your profile, if you’re vac banned, there will be text near where your badges are normally displayed.
Can you check why someone was VAC banned?
VacList allows you to view and track Steam accounts and their ban status. You can search for accounts by either their SteamID, community URL, or vanity name. Logging in through Steam allows you to track accounts and view their ban status over time.
How long does it take to be VAC banned?
How long does a VAC ban show on profile?
If you know just one thing about Valve’s Anti-Cheat system (VAC), you probably know that a ban issued through it lasts forever. As Valve’s support page lays out clearly, “VAC bans are permanent, non-negotiable, and cannot be removed by Steam Support.”