The extension for chrome updated to 8.1.1.0 and forgot the M2TS setting was enabled.
I did a side download and found it downloaded a video without the audio.
It's not a site presenting the media separately, so this could be a issue for a lot of users
when extension updates. I assume it'll be the same in Firefox and Edge.
I could have seen this earlier when using the beta in Firefox but it was left with that
setting off. With side downloading isn't the M2TS setting basically redundant now as it downloads perfectly playable mp4 files with no issues like before.