Yes, in some cases banks can freeze the bank account linked to crypto trading, like suspicious transactions, violation of policies, not following the income tax law in the case of crypto exchange, and many more.

So to avoid all these problems completely, do the KYC, use the well-known crypto exchanges, and avoid large and frequent transactions.

For converting crypto to cash, there is a fees and 1% TDS changes. Also Besides 30% tax, 1% TDS also applies.