Say out loud to yourself, "What the hell is this?" or, "Why did they do it this way?" once in a while. Everyone around will think you know exactly what you're doing.

From what I learned in my workplace, it seems that for most people the best way to appear competent is to continuously criticize the work of your colleagues

I don't know your circumstances, but it is usually OK to just ask. Especially if the original author is around. Don't do it all the time and you'll be OK. Even can come with positive image out of it, if you ask the right questions.

Other than that, I found that the current llms like ChatGPT (and perhaps Claude) are very good at explaining code, most of the time, for some languages ;)