Probably referring to the 6-month timed exclusivity on PC that Borderlands 3 went through.
As someone who sunk hundreds of hours into each of 1 and 2, the staggered launch felt like it did so much damage to player base as well as player interest. Felt like when I was interested in it none of the old hardcore raiders I used to play with were and vice versa. And thats after I was the one to crawl to epic because I was afraid of missing out that sweet endgame co op high I got from 1 and 2.
I loved BL1 and 2 so much, my pets are named after characters from the games. The staggered launch of BL3 caused me to forget about it for years after release.