I was awful for years. It took a lot of feedback from strangers and friends a like. I committed every "bad DM" sin from those list videos on youtube. I've railroaded, overstepped social bounds, been adversarial, and so on. I could write a 1000 word essay about how bad I was. I could cite which campaign I learned which lessons in. It took years of feedback and reflection and progress was slow.
To be honest, I still think I'm pretty bad, now seven years in. Seven years of asking for feedback after every session. I still make pacing mistakes, break tone, and push combat a bit too much. I still struggle to pull together story lines throughout a campaign for a good conclusion. I still sometimes dont reward players in satisfying ways. I'm awful at narrating combat, often offloading it to the players. The areas for improvement are many.
Yet people continue to play with me. Strangers even. Almost all of them, actually, stick it out and play to the end. Because no one expects perfection. Most are just happy to play.
My advice to any DMs, especially new ones. Ask for feedback often and have humility and grace. And never stop trying to be better. DMing is hard.