Many years ago I found myself in a similar situation with a different outcome.

No IPO or corporatization of the company (it was a non-profit), but a colleague who got their start working in a particularly soulless branch of advertising was promoted to management - specifically, my manager. They set about eliminating every position in my department and replacing them with contractors. Well before they had set their eyes on me, I knew the game was afoot, and was desperately trying to get out of the company, but at the time, the job market was absolutely terrible. They began by cutting the meager standard raise the company gave every year, criticizing my work and work practices, and putting me on a performance improvement plan. So I meticulously complied and documented all of their demands and the steps I’d taken to resolve those demands.
At the conclusion of the PIP, my manager scheduled a meeting that included her boss - the COO of our organization, and they started the meeting by both flipping open identical folders, reading out what the PIP had stated, and saying that they felt I had not made satisfactory progress, and then attempting to move to the next set of papers in their folders. I (politely) interrupted by opening my own folder with several printouts. I could see the COO visibly disengage and go a little cloudy-eyed. They were not really paying attention. They were simply waiting for the conclusion of the meeting, so they could fire me.
The printouts I provided to them were fairly comprehensive, including information that detailed every daily ‘huddle’, every weekly ‘touch base’, every spontaneous meeting, and every catchup chat conversation with dates, times, and summaries of the meeting, as well as a count (but not comprehensive) breakdown of every email my boss had been CC’d on (which was every email I’d sent from my work account during that time period). I briefly ran through the information, and said something to the effect of “The effort of keeping you informed of my work projects currently consumes about 20% of my work time, as you can see. I don’t know how to better inform you of my work processes, but I’ve fulfilled everything on the PIP, and if you feel there’s more I can do, I’d be happy to oblige.”
The COO was still disengaged, with a practiced expression of boredom. I continued, explaining that in the time that my manager had taken over her role, I’d noticed a definite behavior and attitude shift from her. I said that I felt she had gone from being a friendly colleague to someone that treated me with hostility. The COO blinked hard, and actually looked at me while I pretended not to notice. I continued, saying I felt that my boss had made an effort to make the workplace less welcoming to me (noting several examples where she’d enforced personal policies that were not backed by or were contrary to company policy). The COO shut their folder. I asked how we can move forward. My boss was about to speak, and the COO jumped in, saying that this was all good, they were going to terminate the PIP immediately, and to keep up the good work. I never got to see what else was in their binders, but my boss looked upset. They later had to attend managerial training.

I left a few months later to a great job that is still mostly enjoyable nearly a decade later.

I guess my point is - if you find yourself in a similar situation, document it all and don’t be afraid to insinuate you’re going to sue the shit out of them for creating a hostile workplace while you line up other plans.

Oh, and there’s no shame in telling your therapist that self awareness does not equal the ability to solve or develop coping strategies. Often, being able to identify and fluently discuss how you feel about something does not come with an ability to identify how you can overcome/avoid that problem or successfully manage your feelings about it.