My thoughts on Mia's inheritance.
I wonder if there was an older couple that Mia was involved with (perhaps a sex worker throuple situation), who left her some cash in their will.
Or more likely an elderly sugar daddy that was not Gordon.
That makes more sense than fairy grandparents who let you go into foster care but leave you a ton of money after they die.
At this point, any pretentiousness about this show being upper-crust has been flushed down the toilet.