Just reading the abstract, it talks about finding a number of bugs (across millions of lines of code) but I didn't see any claims that there would be fewer bugs in a different language.

Go obviously does not stop you from writing buggy code. Neither does rust or zig or whatever. Does go make it more likely to have bugs? Or a specific class of bug? Like, the real world is about trade offs.

Uber has fairly large golang and java codebases so they have more of an apple to apples comparison here since they are both GC languages of a similar performance class. And if a large population tends to make more mistakes with 200hp sedan A vs 200hp sedan B, there is probably something up with the design of sedan A.