The problem shows up on my tax claim in my country. I can't by 12 Lambos and say oh I have earned them with my 3000$ sallary (I have 900$ sallary and average in my country is 450$).
They will ask how did you get it. If I say I earned on investment in crypto, they will not recognize crypto and then what. Bank statement ,,I got it from that account'' is not gonna work.
The question remains how did I earn it.
And how did a prostitute earn it? How did a gambler earn it? There are situations where you simply can't register a business and get an accountant to keep the books.
In some cases you simply earn money from sources that the government doesn't want to recognize, but as long as you are not a criminal and pay taxes the bank has no right to hold your money without processing it. They can refuse to service you, but they can't take the money or claim it was obtained illegally.
I wouldn't worry too much since this is a free and open market. If one bank doesn't process it another one will, just make sure to let people know which bank is making difficulties so that people don't waste time with them.