We have identified the issue as pomu failing to grab an appropriate playlist url using youtube-dl to pipe to ffmpeg.
However, pomu is currently being rewritten to support a new file format and at current development progress fixing the existing issue does not make sense as the fix will be replaced soon anyways.
As a workaround, some important scheduled livestreams such as unarchived karaoke streams will be recorded manually and uploaded to the pomu-manual
S3 bucket. The download url for these videos will be fixed up soon after the stream has finished.