Hi! Thanks for the feedback on diffs - it's something we're always thinking about and working on in the group.
One of the things we're currently working on is putting monitoring in pace for all the of the diff limits - https://gitlab.com/gitlab-org/gitlab/-/issues/31063. The goal here is that we can further fine tune some of the limits in place to continue to help with larger merge requests.
The group also spent some time investigating ways to improve the blocking time for large merge requests and you can see some of the discussion around that here: https://gitlab.com/gitlab-org/gitlab/-/issues/295237.