I acknowledge that the company decided to trade productivity for saving money on office space, and then I accept that their choice limits me to 50% of my usual

I acknowledge that the company decided to trade productivity for saving money on office space, and then I accept that their choice limits me to 50% of my usual working speed. Maybe I bring this up once, but if my managers dismiss my concern, then I accept that the company wants to pretend that there is no tradeoff. Accepting these things makes it a bit easier to not worry so much. In your specific case? Let your manager know that this task requires more focus than usual, and ask them if they would prefer that you book a conference room for 4 days or WFH for 4 days in order to concentrate on it. Honestly, I think the only way to stop this idiocy around open offices is for all of us to get ADHD diagnoses, and to claim a private, quiet space as a necessary accommodation for disability.