While I have absolutely no love for Azure, it's worth pointing out that doing a migration, any migration to a new environment can often be an opportunity to clean up and fix old junk that has not gotten attention, and that issues in a new environment often end up being treated as a problem caused by the migration and given attention and fixed, where the same issue might have been ignored in the old one because "it's always been there".
As a result it's often really hard to tell if all the differences are down to differences in quality between the two providers vs. things done as part of the migration.
But of course this also does not mean the providers aren't different in terms of quality, just that it takes more than a graph like that to tell.
I feel like those posted uptime/reliability numbers are far lower than either GCP or azure is capable of providing. I suspect the majority of the errors/failed requests are probably code bugs or deployment issues in gitlab...
Perhaps they haven't been doing enough chaosmonkey testing?
As a result it's often really hard to tell if all the differences are down to differences in quality between the two providers vs. things done as part of the migration.
But of course this also does not mean the providers aren't different in terms of quality, just that it takes more than a graph like that to tell.