Media Encoder Poor Quality MP4 exports and conversions

First off, I've always used Handbrake instead of Media Encoder when a client needs a very small, compressed mp4 for web since it seems to do a much better job.  But recently, I've come across a quality issue even when converting a ProRes file to MP4 using the default "Match Source- High bitrate" preset in Media Encoder.  It only happens in this one spot in this one video.  I've never encountered this before but wonder if might've happened to a lesser degree in the past and I didn't catch it.  When I use Handbrake for the same conversion, it looks fine.  See attached screenshots of the ProRes file and the Media Encoder MP4 conversion. 

Media Encoder team:  I can send you the original ProRes file if you'd like to investigate.

Spec:

Macbook Pro M1 Max, 64GB, Ventura 13.2.1, all latest Adobe updates (Premiere & Media Encoder 23.5.0)