I’m seeing the same problem since two releases back.
Two remote users on Roku fave the problem for all transcodes. One of them also has the problem on a 2018 Samsung client with all transcodes.
I can reproduce the problem locally on a Roku, but only with videos that have ASS subtitles and the Roku client burn subtitles setting as always (doesn’t happen if set to burm image only).
In all cases switching transcoder from UHD 630 to Nvidia fixes it.
I submitted my report yesterday, not having seen yours.
