Thank you for your response.
The built in youtube renderer, in my opinion, takes significantly longer to upload to youtube. Also, I sort of like having full control over the final image. Bit nitpicky in that regard.
So it looks like both of your suggestions to go two pass solved the issue. Either CBR of 10,000,000 or VBR with two pass works for the mp4 format that I like exporting in. I’ve uploaded a 3 minute clip that displays the blotchiness I was referring to. Just waiting for the moderator to approve it.