opus can’t be tagged

I'm pretty sure that it supports tagging.

goes to try it out

$ yt-dlp -x https://www.youtube.com/shorts/syF8M3aeiWs >/dev/null
$ opustags beep\ sound\ effect\ \[syF8M3aeiWs\].opus |grep -v ^METADATA
language=eng
encoder=Lavf61.7.100
title=beep sound effect
date=20230316
purl=https://www.youtube.com/watch?v=syF8M3aeiWs
synopsis=beep
DESCRIPTION=https://www.youtube.com/watch?v=syF8M3aeiWs
artist=Seth's old channel 
$

If you mean that this MusicBrainz Picard thing doesn't support tagging Opus, it sounds like it does:

https://community.metabrainz.org/t/musicbrainz-picard-doesnt-support-opus-files/467209

I have been having trouble tagging .opus files. Every time I try to edit .opus files I get:

(error: read b'\x1aE\xdf\xa3', expected b'OggS', at 0x0)

Looks like this is not a valid Ogg Opus file. Opus is just an audio codec, not a file format. Files with the file extension .opus are supposed to be inside an Ogg container, and that’s what Picard supports.

Your’s seems to be a Matroska file, and Picard does not support Matroska files yet.

And looking at the output of yt-dlp -x, it looks like it's Opus in an Ogg container:

$ file beep\ sound\ effect\ \[syF8M3aeiWs\].opus
beep sound effect [syF8M3aeiWs].opus: Ogg data, Opus audio, version 0.1, stereo, 48000 Hz (Input Sample Rate)
$

EDIT: Note that my ~/.config/yt-dlp/config file is:

--embed-subs
--write-auto-subs
--embed-metadata
--embed-chapters
--embed-thumbnail
--sponsorblock-mark=all

It may be that one needs --embed-metadata on the yt-dlp command-line if one isn't setting it in their yt-dlp config file to get the above tags; it might be that none normally get set.