Typically this is not something you worry about too much. You work on a research project, you talk to people around you, your research manager and everyone around you pretty openly, and if something was going very wrong, you'd likely know because someone would have told you along the way. So by the time you are submitting for internal review, the expectation is that you will almost certainly pass, but typically the reviewers tale their job pretty seriously (and so did I when I served as one) and spent a week or two reading through your paper in their "spare" time and writing a comment on the science, the method, the conclusions etc. The not-leaking-secrets part is certainly there, but that's the lowest bar to pass, so one rarely worries about it practically if one works on public datasets and doing fundamental science.
My experience might be different from what Dr Gebru was going through since I never rubbed against anything that could have been considered company secret. My work was entirely academic and I never felt that I was restricted in any way in the questions that I could ask or the papers I could write. That is likely very different when you are criticizing a product, using internal data etc, which might have been the case with her. It also seems that she was in no way diplomatic about her actions.
When you do fundamental research there, it's as free or possibly even freer than standard academic institutions. As I said, I personally never felt any implicit let alone explicit forces telling what to work on / what to avoid.