Which is something I always try to explain to juniors: writing code is cool, but for your sake learn how to READ code.
Not just understanding what it does, but what was it all meant to do. Even reading your own code is a skill that needs some focus.
Side note: I hate it to my core when people copy code mindlessly. Sometimes it’s not even a bug, or a performance issue, but something utterly stupid and much harder to read. But because they didn’t understand it, and didn’t even try, they just copy-pasted it and went on. Ugh.