Just confirming, you are now seeing this on 6.5.12 with freezing?
As I re-read this, what is attached to your Framework and how is it attached? So I might try to replicate this.
I’ve seen issues with DMUB in the past, namely Debian.
But I have yet to have the stuttering experience you described. So I’d like to replicate the setup for replication on my end and potencially a bug report.