First of all I want to apologize to you, I made a very low level mistake, I have fixed the error in the code, you can try to re-enter through your session ID, again I apologize.
Actually I don't have 20tbtc, that introduction is from chipmixer, I only have about 0.5tbtc to test, because it's a test program, so this aspect is not done very rigorously, theoretically, it should be introduced next to the recharge address of the maximum recharge amount allowed, thank you for the test!
Apology accepted, and everything is working again, but you are lucky that this was only testnet bitcoin. Actually I don't have 20tbtc, that introduction is from chipmixer, I only have about 0.5tbtc to test, because it's a test program, so this aspect is not done very rigorously, theoretically, it should be introduced next to the recharge address of the maximum recharge amount allowed, thank you for the test!
If you don't have 20 tBTC than you need to make a correction on website to avoid confusion, and write maximum amount of coins that are available before mixing procedure started.
And how can I know that private keys are not stored on some cloud aka hard disk?