Are there any negative side effects of splitting up large modules? [closed]

Question

I was browsing a github project and found this module which has more than 10 thousand lines.

Is it a common practice to have that much code in a single module?

It seems to me that this should be split over multiple modules. Maybe one for each db engine.

What benefit does the developer get from making one huge module like this (other than "having it all in one place") or what downside is there from splitting it up (other than "complexity")?