Hmm, to me it sounds there are some missmatches. If your camera resolution is 1080p60 then there is no point in streaming in any higher resolution than that. 60fps could be another issue. Movement looks un-natural at higher fps, unless this is a wanted effect or you really have high movement. I would recommend 30fps. This has two things to consider. The camera chip has twice the time to expose an image. This means that you need less light or can close the iris more which is often reflected in amplification by x db compared to the 60fps.
Almost the same applies to streaming. 60fps needs twice the bandwidth than 30fps.
Please try a 1080p30 and step up the codec profile and bandwidth. This would have the most impact on quality. And please think of users with mobile devices attending your stream. Bandwidth and screen resolutions might be poor compared to computer screens.
h264 vs h265 is another topic to think about. You will get lower bitrates at the same encoding quality with h265 with the cost of encoding power and most impacting at the receiving side. The more you compress, the more you have decompress. Older devices might simply struggle with the load.
Bandwidth consideration can be understood in compression as well. The higher the bandwidth the less compression. Ideal would be no compression to receive exactly what you ingest. But that would mean at 1080p60 you would need 6 Gbps constantly. This is unrealistic. The less compression the less compression artefacts.

I hope this gives you a better understanding and a new approach to optimize your settings.

We have been doing this for about a year on the live streams of swimming events we do.
Our cameras are all 1080p50 but we upscale to 1440p and that triggers YouTube to offer VP9 as a codec for people watching.
I spent many hours reading forums to try and find a way to encourage YouTube to encode with VP9 and this was the only way that worked.
I have just checked one of our streams here ?list=PLvjxIeuyT-6qP3orLzW1lgwbe7bsaQuY6&t=9783 and it is still using VP9.

That channel has ~1900 subscribers. I believe the bigger your channel the more likely it is that YouTube will use VP9 for lower resolution streams, which makes sense as they don't want to use the extra processing required to offer VP9 unless it's worth it.

Our opinion is it is worth the effort, even though our cameras are only 1080p the quality saw on our local 35mbit/sec 1080p recordings was so much better than the old AVC1 codec YouTube used, and 'encouraging' YouTube to offer VP9 to our eyes gives a much better quality stream which getting closer to our local recording.

Regards,
Mark Leman

I was talking about how YouTube encodes it. It just seems that they aren't going to give you the VP09 codec regardless of what you send them until you get a lot of followers. However, I did notice that during the livestream it was VP09. As soon as it ends, it switches. Not sure what that's about. I guess they are processing it after the fact.

I compromised at 10 mbps, 1080p 60fps, with P5 preset using HEVC. It seemed to be a good balance and the laptop NVIDIA 3070 GPU was around 40%. These presents P1 - P7 really trigger the most GPU processing. From P5 to P6 is a big jump and P7 is way too much for the hardware for little gain.

The only reason I used 60fps was to smooth out a little blurring when someone walked across in front of the cameras. These are PTZOptics 20x NDI cameras.

I could always switch it back to 30fps, but for now I'm going to see if it remains stable.

I understand your point about the the framerate.

After some soak time, I may switch it back to 30.

Thanks for the feedback.