For those saying to move away from Barclays, go to another bank, Please note that this happens with all the banks. If you had been with anyone else, the exact same thing would have happened.
You have been flagged for suspicious transactions. Most likely the large amounts being transmitted back and forth to overseas accounts due to gambling on the Crypto casino.
The massive negative is because you are under investigation. You will unfortunately get no information while they do this.
You had better hope that the Crypto casino is behaving themselves as this can be the result of that casino doing some dodgy things of which your are unaware.
I hope it gets sorted soon, but all you can do is wait.