Re: Roku ultra 2020 SD mkv playback aspect ratio issues
Since there hasnt been a firmware update since early February (9.4.1-4236), and thats the only one since the OP (not that the issue couldnt have or didnt predate the OP), you'll probably have to wait another build or 2 before this is likely to be fixed (6-12 months or never are not uncommon fix times for Roku).
Its also likely OS 9.5/OS10 will drop before another 9.4.1 build does at this point (should be announced at the end of March/early April), and that will likely add to the fix time.
StreamerUser Roku Community Streaming Expert
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