custom_format selection not being respected

[ak-42]

Hello. Firstly, I'm deeply thankful for this project, it allows me to watch YouTube offline and without algorithm and that's a big win for me.

I think I've encountered an issue with custom_format option. My config file has this:

quality = "custom"
custom_format = { youtube_dl_format = "bestvideo[height<=1080][vcodec=av01]+bestaudio/bestvideo[height<=1080][vcodec=vp9]+bestaudio/bestvideo[height<=1080][vcodec=avc]+bestaudio" }

However, despite checking that the video(s) in questions have av01 and/or vp9 versions available, podsync still downloads the avc version. I thought it might be a yt-dlp issue, but if I run the following command, the correct av01 or vp9 version is downloaded over avc (for the same videos that podsync fails to download as av01 or vp9):
yt-dlp -f 'bestvideo[height<=1080][vcodec=av01]+bestaudio/bestvideo[height<=1080][vcodec=vp9]+bestaudio/bestvideo[height<=1080][vcodec=avc]+bestaudio' YT-URL
I can also see that custom quality is selected in podsync logs, but the output is just avc.
The logs say: level=info msg="-> updating FEED-LINK" feed_id=FEED-ID format=video quality=custom
I don't have max_height defined in my file (in case it could interfere with custom_format).

Am I doing something dumb or is podsync somehow failing to pass these parametres to yt-dlp?