GitLab is great and has come a very long way over the last several years. However, I still gladly pay GitHub $7 a month for my private repos because I feel that GitHub truly does offer a better code review and repository experience. GitLab in certain places is still very rough around the edges, not to mention performance has always been a concern.
To me, GitHub still is the gold standard and will likely be for quite some time.
Not sure how, it's got the same here is your changed files and the changes.
I find GitLab is better on a few point. You can theme it from about 4-5. I prefer the dark theme as it matches my IDE and easier on my eyes. You can also have comments marked as addressed. By default the changes are shown in the page but you can also choose to show side-by-side like in GitHub.
You can host it yourself. It ties in very well to it's own CI/CD service and comes with a docker registry. So your code can be tied easily to your deploys and you see this in the issues.
To me, GitHub still is the gold standard and will likely be for quite some time.