I try to play online but within a couple of minutes of the match starting I will be kicked and it says client integrity violation. I haven't played in a few months but this did not happen before and I was wondering if there was a way to fix this.

You may consider trying this.

GAME SECURITY VIOLATION DETECTED ERROR

1. Run Steam and click LIBRARY.
2. Right click on Insurgency: Sandstorm > Properties.
3. Click the LOCAL FILES tab and click on the BROWSE LOCAL FILES button.
4. Open the EasyAntiCheat folder and run the EasyAntiCheat_Setup.exe application.
5. Select Insurgency: Sandstorm and click on the Repair Service button.

For any issue with Easy Anti-Cheat (EAC), please submit a ticket to their Technical Support:
https://www.easy.ac/en-us/support/game/contact/tech/

More info: https://steamcommunity.com/app/581320/discussions/2/1742228532896888962/

@Brandon-M hello its tell me the same, u now know how to play??