I haven't modified it myself in any way, nor am I playing with any mod that modifies that IIRC. But as I said, I had no idea what a "small fleet" entails. All my cargo vessels were fast frigates, Hermes, Dram and Cerberus ships, I was using a Hammerhead as my flagship, and I wanted as many Drover carriers as I could fit in, one for each officer, since they are the fastest carrier. I just slowly expanded my fleet with nothing but these small fast ships, and I noticed that I lost the ability to disengage. I can't know when was the exact point this happened, but I'm pretty sure it was when I still had only 6 officers, So I didn't have like 10 Drovers yet.
Then I had no idea how to downsize, so I wrote here. Like what was I going to do, remove one carrier or frigate and try to run into a fleet that would fight me? That just seems unnecessarily tedious. If I want to "beat the game" on ironman, I thought that obviously the best strategy is to use a small nimble fleet to gather enough money to get a fleet of sufficient strength all at once, to reach a point where you don't want to run away from any fight - all at once.