I was a member of STS and I can say crowdsourced translations were a million times better than the now-paid translation teams Valve hires.
And yes, while it was mostly "unpaid", during my time there (2016-2020), we had a year-end rally every year which the "fastest" teams to complete translations would receive Steam wallet codes for their effort. I received up to $350 the first year of rally.
The next year they gave us Artifact keys...
and then the one Valve employee managing the server left Valve, and STS was slowly being replaced by Crowdin
they essentially killed crowdsourcing starting with Artifact. We (the STS members) had no access to new strings, then came Underlords, the new client... Only TF2 translations are crowdsourced to this day. The rest are done by their external teams.
Allegations of unpaid labor are for crowdsourced translations and have nothing to do with Valve as a workplace.
This controversy is known and there are a few translators on Steam/Valve that came from the community, but nowadays it is mostly outsourced, and they do a terrible job (they replaced gamers with people who can't even bother to download the game to check the context a string is applied to).
As for the second, I'm confused as to why anyone would provide unpaid labor to a large, profitable corporation.