I agree that in your example it is not bad. Throughout that codebase it is clear though that they don't have a formatter that enforces a char-limit per line. It is when you combine those things it gets messy. Prettier uses a default of 80.
Looking at the code there is an awful lot of 'null's returned which I find hard to work with but that is a different topic.
The typings on the class variables are useful to have. There are also typings on the function signatures, not a huge deal.
In the method bodies there are almost no typings as all of it is already inferred. Seems pretty readable to me.