Trading away draft picks lowers future cap space

I first noticed this in my offline franchise after a huge drop in future cap space after trading for a guy on a one-year deal so I quit without saving and I'm trying to figure out the math behind future cap space used for negotiations.

I have 56.4 million in cap space for the current season, 38.1 million in rookie reserve (lots of acquiring future draft picks), and when I go to resign guys it says I have 44 million for 2032. In testing, I traded 3 2032 first round picks away for a 2034 1st, 2nd, and 3rd as something that shouldn't factor into this season or next season. My 2032 rookie reserve then fell to 21 million. This drop of 17.1 million makes sense to me, those 3 picks should be a good chunk of what was reserved. When I go to negotiate with guys after this, it says I have 15 million left in 2032 cap room.

Why would a 17 million dollar decrease in money I need to hold for draft picks lead to a 29 million dollar drop in money to sign players? If anything, I'd think it would give me more money to negotiate with players if that money is no longer being held for draft picks. Am I missing something obvious here? I did this all at once so it's not like the draft picks changed their projected pick number/allocation tied to each one. I haven't submitted any offers so it's not like any money is tied to an unsigned player, this is all going off of the starting negotiation screen.

I played week 3 and went to the next week. The Reserve increased by 2.5 to 40.6. The 2032 cap stayed the same at 44 million. This is even more confusing because that would mean that the week to week change has nothing to do with future cap, but the act of trading away picks somehow hurts it. I tried trading the 3 first round picks from earlier for a 2034 7th rounder and again lost 29 million in 2032 cap despite lowering my reserve by now 19 million.