Can you verify whether third-party applications adhere to the Identity ...

The other, and not so obvious issue, is that even when using certificates, the vendors might have opted to implement their own wrapper, instead of leveraging the built-in MSAL methods. While this is an acceptable behavior, Microsoft recommends to stick to using the MSAL methods, as it allows them to implement additional security features on top of the module, such as the ones detailed in Alex Weinert’s session at last year’s Ignite.