How can I make my left hand good as my right hand in piano?

I have been playing piano for 30 mins everyday from around 2 years. My right hand have improved a lot but my left hand can't become fast. The maximum I can do from left hand is playing three keys at a time.
This is my YouTube channel. You can see the right hand is pretty well but left hand can't do much. The most nice performance by my left hand was in the piano cover of Believer. You can check it out. Please share some tips to make a stronger left hand.
How can I make my left hand good as my right hand in piano?
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