Firstly, it's a generic phrase for messy code. Secondly, the formatting made non-messy code look messy because of the formatting and extra brackets that aren't required. Just like declaring an int inside a for loop body which is another thing I've seen functional programming in java advocates do a few times.

First of all, if a couple of curly braces make your code hard to maintain, r/python is this way (I say this with 8 years of professional python experience). Also, it is my opinion that arguing about formatting is for chumps. Use a code formatting tool that is consistent. I recommend prettier with the java plugin. It'll save you a lot of headache, because you'll stop worrying about whether or not there are curly braces on a single line if, and spend much more of your time worrying about the code itself. Don't argue about tabs vs spaces, how many spaces, curly brace placement, spacing, etc. Just use a tool that has opinions for you, because it ain't worth my time, I have too much shit to get done at work.

The "difficult to maintain" bit is most relevant.