In recent years, football has become a sport in which a team's financial situation has greatly helped in its achievements in domestic or foreign competitions, and it seems to me that in the Brazilian league, the smaller teams are in better financial conditions when compared to the smaller teams in the leagues of other South American countries, as is the quality of the squad, which is why I'm not surprised to see Brazilian teams having a better chance of winning South American competitions and even in cases where they don't win, at least Brazilian teams manage to go further.
Brazilian football is in a phase of professionalization of football management, which was initiated by Flamengo and Palmeiras, and soon after the "SAF" entered to invest heavily in football and clubs, so it is somewhat natural that Brazil stands out in these championships, the rest of the clubs in South America are falling behind in management (I believe)... This for me is one of the reasons for all this difference.
Exactly, this issue of alternation is so important to create competitiveness that we don't have a team that always wins. Brazil is really at a high level in South America. But, there is still a long way to go before it can get close to European football.