No one else can see your tax return so we do not know why you owe.   There can be many reasons why you owe tax including not having enough tax withheld from your paychecks, collecting unemployment and not having tax withheld, losing the child tax credit if a child turned 17 during the tax year, entering some data incorrectly, etc. etc. etc.   You should print out your return to compare it line by line with your 2019 return to see what the differences are.   

As for your stimulus---did you use the recovery rebate credit on your 2020 return?   You need to do that so that any stimulus still not received can be included as part of your 2020 refund.

The stimulus check is an advance on a credit you can receive on your 2020 tax return.  If something went wrong or you did not get the stimulus check in 2020, you can get it when you file your 2020 return in early 2021

The Recovery Rebate Credit will be found in the FEDERAL REVIEW section. ( you should see "Let's make sure you got the right stimulus amount”)  If you are eligible it will end up on line 30 of your 2020 Form 1040.

Make sure that you enter ALL of the stimulus money received for the 1st ad 2nd stimulus for yourself, your spouse and your children.

https://www.irs.gov/newsroom/economic-impact-payment-information-center-topic-j-reconciling-on-your-...

https://ttlc.intuit.com/questions/1901539-how-do-i-preview-my-turbotax-online-return-before-filing

Click on Tax Tools on the left side of the screen. Click on Tools. Click on View Tax Summary. Click on Preview my 1040 on the left side of the screen.

The amount of taxes owed is based on how much was paid in during the year. If you had changes to your income, such as collected unemployment, it could have changed how much was paid.

For your stimulus payments, this is reported in TurboTax by following these steps:

1. Go to the search box and enter stimulus. Click the Jump to link.
2. Answer Yes.
3. At the next screen, Let's double-check the amount you received, answer No to edit the first-round and second-round amounts.
4. If no stimulus amount was received, enter 0. An amount should be entered in each box. When finished, click Continue.

You may want to adjust your withholding for 2021 for the federal and for any state taxes to make sure you have enough taxes taken out going forward. 

For other ideas, see: 7 Best Tips to Lower Your Tax Bill

How do I update my 2020 withholdings and print a new W-4?