It is hard to say what caused your tax to go up more than the 15% capital gain tax with such limited information. It could be that the capital gain put you in a higher tax bracket. You should review your entry for the sale of Bitcoin to make sure it was entered correctly, both the amounts and the holding period.
You can review your tax return and the applicable tax worksheet used to calculate your tax. To do so, you will have to pay for your return before filing. For instructions, see this TurboTax Help Article: Can I print a copy of my return in TurboTax Online before I file it?
Adding income to a tax return can have side effects besides the direct tax on the added income. The increase in income could reduce or eliminate various deductions or credits that are not related to the income that was added, but that have income-based limits or phase-outs. You have to compare your Form 1040 line by line before and after adding the Bitcoin sales to see what else is changing besides the amount of capital gain. If there's a change in an amount that comes from another form or schedule, you have to look at that form or schedule to see what's happening.