No, generally speaking, when you have a memory leak within OBS, your CPU usage (regardless of encoder) just continually rises and rises and consequently your FPS drops until theoretically programs would start crashing because OBS would literally use 100% of your CPU.
Duplicate your current Scene Collection and start to remove the sources one by one until you find the source that cause the leakage (this is general steps to find the leakage). As were mentioned by @RytoEX, start from browser source, then video capture device source (webcam), then others.
If you have any crash-logs from OBS Studio, please post them too (Help menu).
A memory leak causes increasing use of memory, not CPU..
I've heard and read that a memory leak causes your CPU usage to rise until theoretically it would max your CPU out and programs would start to crash? Either way, my CPU usage WAS rising until FPS was affected when I used OBS with Browser source installed and ever since I installed OBS without Browser source, I get zero memory leaks and my CPU usage also doesn't rise. Keep in mind, I don't even use the X264 encoder. I've used NVENC for quite some time.
No, that is not a memory leak, a memory leak has nothing to do with CPU usage.
Browser source also uses CPU and GPU and how much depends on whatever you have running in the browser source.