Most of everyone's main reason was that GitLab was "open source" and also supports free software. As much as they claim to do, I'm afraid that by being partially owned by VCs, they are at the mercy of pleasing those who may conflict with these ideas in favour of adware such a telemetry or ad-tracking.
A very principled move from GitLab to revert this, but I think that GitLab's trusted is damaged due to this.