This one is already in the default uBlock filters - Badware risks
I also strongly suggest adding https://big.oisd.nl/ as a filter list. It's a large and well maintained domain blocklist (sourced from combining lots of other blocklists) that usually adds lots of these sorts of domains quickly and has very few false positives.
Before trying the conversion, I suggest checking if you are missing a library that strawberry needs (probably libopus or libopusfile). For me, strawberry reads opus files perfectly normally, so I wonder if yours is falling back to using ffmpeg or something to decide them
If you really must convert, use Vorbis with the variable bitrate mode -q6 (or -q:a 6 option in ffmpeg) which usually ends up around 192 kbps, or push it up one more to q7 which will be a little higher. This is the level that is usually transparent, but do keep in mind that any conversion between lossy codecs is much more likely to cause perceivable loss in quality than a conversion from a lossless source. Btw opus is the direct successor to Vorbis and is superior in quality per bitrate (128k is what YouTube uses and is indistinguishable the vast majority of the time). It's probably better than 320k mp3 at least
Out of 4,037,953 GitHub user profiles with email addresses, we were able to identify 1,426,121 (35.3%) of them as men or women through their public Google+ profiles.
Could be a confounding variable in that the type of people who reveal their gender publicly might differ from those who don't in some way that is also related to their contribution quality