I am definitely seeing this on my Roku TV on 9.3.
Live TV, that is to say - non-transcoded MPEG-2 video, directly streamed from an HDHomeRun via Plex, will freeze but audio will play on.
This behavior is new to Roku OS 9.3. It worked fine before.
I've switched back to using Tablo for watching live TV, which transcodes so it isn't subject to this behavior, but there's definitely an MPEG-2 decoder issue with the latest Roku OS.