The law passed either last year or the year before, I can't remember, and it's going into effect this year or last. There's also a social media ID law as well, but I don't think it has gone into effect yet (I don't use SM aside from Lemmy, so I haven't noticed, but occasionally follow Twitter links).

I just checked, and xvideos works fine, but xhamster has a "start verification" pop-up upon page load that requires uploading my ID, or logging in if I've already verified myself. Pornhub just refuses to load with a protest screen with the following text:

Dear user,

As you may know, your elected officials in Utah are requiring us to verify your age before allowing you access to our website. While safety and compliance are at the forefront of our mission, giving your ID card every time you want to visit an adult platform is not the most effective solution for protecting our users, and in fact, will put children and your privacy at risk.

In addition, mandating age verification without proper enforcement gives platforms the opportunity to choose whether or not to comply. As we’ve seen in other states, this just drives traffic to sites with far fewer safety measures in place. Very few sites are able to compare to the robust Trust and Safety measures we currently have in place. To protect children and user privacy, any legislation must be enforced against all platforms offering adult content.

The safety of our users is one of our biggest concerns. We believe that the best and most effective solution for protecting children and adults alike is to identify users by their device and allow access to age-restricted materials and websites based on that identification. Until a real solution is offered, we have made the difficult decision to completely disable access to our website in Utah.

Please contact your representatives before it is too late and demand device-based verification solutions that make the internet safer while also respecting your privacy.

The checks are all on the service side, not the ISP, and Pornhub lays out the rest of the problems here. I assume Utah would sue noncompliant companies.

So the simplest solution for people in Utah is just to use a VPN in Colorado, our next door neighbor, which adds minimal latency (like 10-20ms). I'm in the process of setting that up for my Wi-Fi network so nobody in our network needs to show ID.