Revolut had (have?) questionable ownership and hiring / business practices when they first started – it was in the press and may even have been discussed on here.
I still use them.
Re the banking licence – they aren’t a full UK bank yet, but getting there. Be interesting to see how they handle the e-mi designation in other countries when they get the full licence. Don’t know the rules on how that works.
In theory, your money is “safeguarded” by their own protections but it’s not FSCS protected.
To answer the OPs more specific case –
If you’re getting paid USD in Malaysia, I’d expect a Malasian entity to be able to offer you a USD account? I wouldn’t use Revolut as your main account.
If you’re getting paid USD to a US account, good luck to you the US banking space is about 2 decades behind the rest of the world ;)