I've used stem splitters, as they are called. Some are online and of course the one in BB.

In my opinion, they are all about the same quality when it comes to results. With the ones I've used, they're all using subtractive technology. Meaning that the stems, or tracks extracted are less than the original.
Bass and drums and some vocals come out fairly well. I'd say in the 95% category. Solo the tracks and you can immediately tell there's artifacts and missing data.
The guitar and piano and other things like background vocals are often iffy at best and are in the less than 50% category.... Essentially unusable for commercial purposes.

As such.... I usually only use the drums and bass stems in my projects and occasionally replace those with solid tracks. I've found a workaround for cleaning up the vocal track.
Hopefully, the way AI and stem extraction is going, in a short while, the stem extraction will completely regenerate the stem track and provide a quality track that emulates completely a track played in a studio rather than the artifact, fuzzy, phasey sounding tracks they're calling stems now.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.