I know for sure, from a friend working in a visa agent and event company, that those are not tourists.
There is now a no. of traffickers, bringing in large groups of Russians under all sorts of visa - related scams. Corrupt 'facilitators' are having a field day .....
Such as Thai - language schools, Gyms (?) are full of Russians.
But of course, the main group are Russians here working online for their Russian employers, just as before, still receiving their salaries in Russia etc.
In I.T. it really often doesn't matter where you work from.