I made less than 10k and paid 70.80 in CA state taxes, but TurboTax says I only get $20 back. Why would I not get the full $70.80 back?

If the earnings were on a W-2, you probably need to check your entries as you may have a typo.   But if the income was from self-employment, those earnings are taxed differently.   CA filing requirements.    Look at your California tax return to see how your tax was computed.