In what kind of call scenario is this observed, and using which infrastructure? It might make sense to have the endpoint logs (from both sides) sent to Cisco TAC for analysis and bug resolution in CE (or VCS, or wherever the bug bight be found).
I have a similar issue sharing with native Proximity 3.x with using Spark Kit codec joined on a CMS cospace. The remote image is jumpy to resolution changes.
Jabber has recently integrated Proximity and I've tested with Jabber 12.6 proximity and it DOES NOT happen there, only on the standalone Proximity located at https://proximity.cisco.com