To sift through all of the noise, the answer that makes the most sense is 1 word: quit
In your own words it “sucks”. If you don’t want it to, your only real options are to accept the new normal, or find a new job. In organizations of that size it will be a grinding multi-year (decade?) marathon to make any company-wide change.
If you’re an engineer, and have an acquired startup on your resume, you should have no issues finding a new role at another company that has your ideal employee size & culture.
Edit: I don’t mean quit today and walk out. But rather, have a new job be your new primary goal and start the search. This will help you get through the days you have left (you’ll be amazed how much mental relief is provided when dealing with a stressful situation, but then realizing - I don’t have to deal with any of this much longer), while being responsible and not leaving until you have a new gig lined up