Hey there, we wrote an in-depth post on the BSL license and why we switched to it: https://datacebo.com/blog/sdv-bsl-license/
BSL is an _eventual_ open source license. 4 years after every version release, that code now transitions to being MIT licensed. SDV's roots are in academic science (MIT), so we wanted to make sure researchers could still use the toolkit for their work.
I'm liking this new approach better than e.g. perpetual AGPL though, as it provides incentives for businesses to acquire commercial rights while avoiding any dead end agreements that outlive the startup entity.