It's interesting to see that GitLab has adopted dual-class common stock structure, though I'm certainly not surprised. Some people and organizations (including some investment firms and stock exchanges) are not fans of multi-class equity structures, but I'm not sure that this fact would have any significant negative impact on GitLab's IPO. At least, these popular 10:1 or slightly less popular 20:1 voting schemes are not as aggressive as Palantir's three-class stock structure, where Class F (just three founders - out of five!) would hold practically 50% of the total voting power.
One strange thing that I've noticed while browsing through this S-1 document, though, is the lack of mention of GitLab's co-founder (Dmitriy Zaporozhets) in the stockholders table (p. 148). I would expect him to hold about the same ownership of the Class B shares as the other co-founder Sytse Sijbrandij holds, but definitely more than 5%, which requires a disclosure there. I'm not sure how to interpret the absence of his name.