Uninstall all mods. Verify your game files via Steam (Right-click Payday 2 > Properties > Installed Files > Verify integrity of game files). If the tag disappears, it was a mod. If it stays, you are running a trainer.
: Ask a friend or a random player in a lobby if your name appears in red with the "CHEATER" label. Check Game Messages payday 2 how to know if you have a cheater tag top
: Using more deployables (like doctor bags or sentry guns) or throwables than your skills and loadout allow. Uninstall all mods