Out of curiosity, how would you change it?
Personally, I'd change the seeding system. I understand why seeds exist, but I think it's
too heavily in favour in the bigger teams.
A higher emphasis on the champions automatically qualifying without the need of entrance rounds. I.E the only teams that automatically qualify are the league champions, everyone else has to go through qualifying rounds. I wouldn't stop the 2,3,4 placed finishers in say, England, from being able to get into it, but they would have to go through qualifying rounds. This would allow the champions of smaller nations, say, Czechia, to be able to qualify.
I'd bin off the away goals rule too, and maybe change the group rounds to have less matches, and more knock out rounds.
So it could look like; 16 league winners or so from various countries get straight through to the knockout rounds, everyone else either has to go through a group qualifying round or something maybe?
I'm sure there's lots of flaws in how I would prefer it to be, but this is just my dumb opinion.