My refund is ALWAYS small, because I INTENTIONALLY adjust my W-4 to match my withholding to my actual tax liability. A refund means you PREPAID too much. The Trump tax cuts not only reduced your actual tax liability, it also reduced withholding, increasing your take home pay in every check
Due to withholding changes in early 2018, some taxpayers began receiving larger paychecks, meaning they were paying less in tax as the year went on. For those taxpayers, that change could result in a smaller tax refund than expected—even if they paid less in tax overall.
Biden has nothing to do with your 2020 taxes. They were all under Trump's watch. Tax withholding tables were lowered in February 2020, so less income tax was withheld. Many people didn't have enough withholding taken from their unemployment and they made more money than they ever had before. Some who receive EIC didn't know they could use their 2019 earned income (if it was higher than 2020) to get a higher credit.
Withholding was decreased for part of 2020, so you got more in your paychecks and less now. You got the same amount in total, or even more than normal; you just got it sooner than normal. And, again, the law requiring this was signed by Donald Trump before Biden became President, and Biden could not have stopped even if he wanted to, because Trump signed a law requiring that it happen.