Your admin sprawl is insane. You've expanded to systems as fast as you could, but haven't kept up on tech and traditions, meaning that your empire has no way to support that sprawl.
If you want to keep playing this game, dismantle any starbases that you don't absolutely need, leaving only the ones near your center. You can keep blocking starbases if you want to retain control of a section of space.
But I'd suggest just starting a new game and not expanding so fast. You don't have to play tall, but you do have to moderate your expansion a lot more than you used to pre-2.2. About 30 over admin capacity is OK until you get to the end of your game, where you can really expand.
Edit: Also, a colonized planet is easily worth about 1.5 times its size in number of systems (so long as those systems have no very rare resources), while it only costs 2+districts in admin sprawl, as opposed to 2 admin for each system. So long as you're within or near your admin capacity, your research and unity can keep you pumping out tech and traditions at a rate that easily matches and overwhelms the AI.