homelab

There is nothing wrong with your proposed design. It’s unnecessary to run the cameras all the way to the same switch as your NVR.

If you're concerned about power, I don't see any reason it should matter at all where you have your cameras, as long as your PoE switch is rated to supply your cameras. If your NVR has some kind of built-in PoE switch, then you can probably avoid having a second PoE switch for your cameras by co-locating them in the same network closet, but PoE switches are so cheap, I'd say set it up however it's most convenient for you. To answer your question of "is it possible," it absolutely is. I'm doing something similar. I have a lot of cameras, but two of them are PoE and are quite a distance away from my NVR server. They feed into a PoE switch that connects to a second switch that acts as the main switch for the building. That switch has a fiber connection to a third switch that lives in my server rack, and that switch has a DAC connection to my DVR server. They work just as well as the ones plugged directly into my rack switch.

The only real concern I see is bandwidth. If your cameras and NVR are on the same switch, you'd avoid having to pass the data from the cameras out across your network to the switch that has your NVR. For 4 cameras, though (even at 4k), your total bandwidth is going to be far less than what even a 1GB network can handle. It's very easy to saturate a switch, though, so this is going to depend largely on your network topology and what you're using your network for.

I would highly encourage you to keep your IP cameras on a separate VLAN, though. IP cameras all have a tendency to want to "call home," and while that might just be for something as simple as checking for firmware updates, I don't want my cameras connecting to anything outside my network without my permission.

Would you be able to draw an ASCII art picture of what you're asking? I'm having a hard time understanding whether the L3 switch is in the same networking closet alongside the PoE switch, and if the NVR is also right next to the L3 switch. Also, is the NVR powered with PoE? Or it needs it's own AC power?