Bitrate fluctuating wildly when streaming to Twitch

[cheekyforever]

I am using OBS with the Apple VT H264 Hardware Encoder. My bitrate has been fluctuating though, going up all the way to 8000 and then back down to 1000.

This is the Twitch Inspector:

And these are my OBS settings:

Is this normal? Are there any settings I can change to run my stream more efficiently? This is a brand new iMac bought specifically for running my streams.