These are just the highlights:
1) My recruitment was a straight-up bait and switch. I was promised a role that did not actually exist, both in formal and practical terms.
2) LinkedIn does not have teams so much as it has reporting structures. IC work is strictly solo -- there's no pairing, there's no collaboration, there's rarely even code review. You will not have any opportunity to learn from your colleagues or build meaningful things. I cannot stress this enough -- LinkedIn is by far the most isolating, disempowering place I have ever worked.
3) Decision making is strictly top-down. Your work is assigned by your manager. Initiative is not rewarded. Credit is not given.
4) You will not build transferable skills. All the internal data infrastructure is proprietary and outdated. Skills you bring from prior roles will have little value here, and skills you gain here will have no, or even negative, value when seeking your next role.
It was clear within a week or two after joining that I had made a terrible mistake, and I left within a few months. I feel terrible for my colleagues that are still stuck there. At the IC level, many people feel trapped, and some don't even realize how bad they have it because they are so walled off from what the profession can achieve. I have had a heartbreaking number of colleagues reach out after I left just to hear stories about what it's like to collaborate in DS, because they've literally never even been told that is a thing. Many have been with LinkedIn for years.
Additionally, it has been brought to my attention in confidence that there are very credible and widespread allegations of abuse and discrimination on my former team. It is not clear that they are being addressed.