Yes, but what's the point of cert expiration? Is it safe to have certs that never expire? I believe there is a security benefit to expiration. Expiration is useless if it's never enforced.
Probably the correct behavior is to have some sort of semi-annoying popup when it expires, and then only a week later do the full blocking. You need to strike the right balance of making it annoying enough that it can't be ignored by everyone (otherwise you just have the exact same problem, just delayed a week) and that fear of it happening is a sufficient motivator to stop people lazily relying on the grace period, but also not too annoying that it makes a lot of people quit. You also want to avoid permission fatigue.
Probably the correct behavior is to have some sort of semi-annoying popup when it expires, and then only a week later do the full blocking. You need to strike the right balance of making it annoying enough that it can't be ignored by everyone (otherwise you just have the exact same problem, just delayed a week) and that fear of it happening is a sufficient motivator to stop people lazily relying on the grace period, but also not too annoying that it makes a lot of people quit. You also want to avoid permission fatigue.