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.