Well, I think that's the reason why they force you to verify KYC since some part of it came from mixers because it is one of their terms they don't allow money-laundering, so may be that is the cause why they force you to submit documents.
Could be, but it wouldn't hurt them to be transparent on the rules and and what would trigger additional KYC/AML requirements. If they had legit concerns about the "quality of bitcoins" then why would they unfreeze it?
And it's important to note that using mixers (or receiving funds from their campaigns) is not illegal and is not equal to money laundering.
What exactly details do you submit about the source of funds? Did you mention it was from a signature campaign?
I ask this because I had a similar issue before, but in local exchanges in my country, I just provided the exact details that it came from signature campaign and the majority of the BTC I held before came from mixers.
After a few days, they unfroze my account and were able to exchange the BTC for local currency.
I might as well post the email I got from them with all the requirements (below).
I essentially just sent them a link to the signature campaign thread + an explanation of what it is, links to the 2 most recent blockchain transactions with a campaign payment to my address, and a screenshot of the transfer from my wallet.
Hello!
Sorry for the long wait for a response, we are still working on your case. Our AML check has raised some questions regarding your incoming transfer.
As we are required to comply with all regulations and laws applicable to crypto exchanges, we kindly ask you to complete an additional verification process.
Could you please complete the KYC process and let us know the source of the funds?
We need a Source of Funds (SOF) confirmation for the Solana (SOL) funds you deposited into the exchange. Please provide one of the following:
1. Screenshots of Withdrawal History:
• If you transferred funds from any other cryptocurrency exchange to Mycelium Exchange, please provide the transfer history, clearly showing the transaction details from the exchange to Mycelium.
• If you transferred funds from a cryptocurrency wallet to Mycelium Exchange, you must provide evidence of where the cryptocurrency was originally obtained. This includes:
• A screenshot of transactions from the exchange or service where the crypto was acquired to your cryptocurrency wallet.
• A screenshot of transactions from your wallet to Mycelium.
2. Important requirements for screenshots:
Screenshots must clearly show transaction details (amount, date, status, and hash), along with the name of the service/platform. Ensure they are unaltered, high-quality, and fully visible.
3. What if the transfer was made for a payment or exchange?
Please provide a contract, receipt, or invoice as proof.
4. What if the transfer was done through an exchanger, where you handed over cash and provided a deposit address?
Please provide a contract, receipt, or invoice as proof.
Let us know if you have any questions. Thank you for your cooperation.
They incorrectly refer to Solana deposit, where the deposit was made with BTC and exchanged to Solana.