Server makes income without trade (taxes)?

Following situation,

A Ps4 Gta 5 Roleplay Server has been selling "Rp" currency for real money for a long time (5 months approximately).

The Rp currency is used by the mykidsbank website. Payment methods are Paysafe Card and there are no receipts or no invoices after the purchase and the money is not taxed.

The problem is that the server owners claim they have a business, but it is not true because they once openly claimed that it was all black money.

The whole thing with the server also takes place on Discord, and they have earned a lot of money (8000 euro + / untaxed)

The owner even showed his earnings once:

There are also enough witnesses who can testify that all of this is true.

can you do anything there?

You can file a criminal complaint for tax evasion. Then it is determined whether there's something to it

Thank you for your prompt reply!

But can I somehow become liable to prosecution because I only give out information about a suspected case.

and how do you submit such applications in the state of North Rhine-Westphalia?