Bipolar here. When I was diagnosed, though not in a FAANG, and asked for accommodation HR, my managers and company owners went against me and fired me. They didn't care about my diagnosis and was against the law but they preferrer to pay me off with a severance agreement and let me go than to understand what mental illness is about.

TBH I don't blame them. This shit is really hard to grasp even to my self. Therefore I only have one very good advice: fake it and never ever tell anyone about it. Not even your friends, less your coworkers.

Mental illnesses are not even understood at medical or research level. I honestly believe this can only be understood by very well trained professionals or anyone who experience the symptoms themselves or from a very close relative. It's really hard to be compassionate with this stuff.

My advice again, keep your mouth shut up, fake it and have a list of very good excuses. Say you have cancer, idk, anything will be better than going out with the mental illness. It's a path of no return and can very well kill all growth in your career as people will talk and place red flags you can't remove thereafter.

Life is way more important than our jobs. Don't try to push more than you physically can, even if you believe you can archive more (specially in mania phase).

Good luck, hope you are doing as well as you can.