There's a lot of problems with telecoms there, but WhatsApp actually has partnerships to enjoy "unlimited" bandwidth privileges with all four mobile operators in Brazil. Just checked and all four have such plans: Claro, Vivo, TIM and Oi.
The bans were because the courts were trying to coerce WhatsApp into responding to subpoenas.
That's still sounds like a wild and unfounded accusation.
And that was partially already the case a few years ago:
TIM started free WhatsApp plans in 2014 [1].
Claro started in 2015 [2].
Oi started later, but it already had a similar plan in 2013 for Facebook Messenger, before WhatsApp acquisition [3].
Vivo seems to be the only holdout, starting in 2018, but that's far from proof that they were in bed with judges just to damage WhatsApp.
And frankly, "you have to read between the lines" sounds like code for unfounded conspiracy theories. Unfortunately something that is currently destroying the country.
You should try to remember the political scenario at the time. The Snowden leaks had generated an immense discomfort in Brazilian government regarding the fact that US based companies could just wiretap Brazilian communications. WhatsApp didn't have a subsidiary at Brazil, and Facebook Brazil used to say they didn't respond for WhatsApp matters. Since Brazilian justice didn't manage to get WhatsApp to answer subpoenas even for extremely low-profile cases, they tried to force their hand on them. The blocks were clearly a demonstration of force, trying to get companies providing services to Brazilians to obey Brazilian law at least to some extent.
There's a lot of problems with telecoms there, but WhatsApp actually has partnerships to enjoy "unlimited" bandwidth privileges with all four mobile operators in Brazil. Just checked and all four have such plans: Claro, Vivo, TIM and Oi.
The bans were because the courts were trying to coerce WhatsApp into responding to subpoenas.