@Garbhanm4 Worth pinning down what your users are actually seeing first. On the Vendor screen (AP303000) and the Project screen (PM301000) there is no expired-compliance warning on the record itself. The only compliance UI on those two screens is the Compliance tab, and the warning sits on the Expiration Date cell of the expired row. Nothing pops at a user just for opening a vendor.
The "Expired Compliance." warning beside a Vendor field lives on documents, not on the vendor record. It fires on Subcontracts (SC301000), POs, Bills and Adjustments (AP301000), and Checks and Payments (AP302000). It's vendor-wide, so any expired document for that vendor lights it up no matter which subcontract it belongs to.
There's no setup flag for any of it. It all switches on with the Construction feature. If you want it off the vendor and project screens, revoke the Compliance tab in Access Rights by Screen (SM201020) for those roles. That hides it for everyone in the role, so check who else uses it first.
AP505000 has nothing compliance-related in it at all. Open the payment on AP302000 though, and the Vendor field already carries the warning you're after. Getting it into the AP505000 grid is a customization.