TL;DR; Lula was the clear favorite for the 2018 election. In a rush job, a new law passed lowering the bar one takes to be arrested (you can be arrested in your second instance instead of going to the Supreme Court if you had a case) and raised the bar on who could run for the office. At the same time, in a Record time, Lula was convicted in the first and second Court instances (by a judge that by "coincidence" took the role of Minister of Justice for Bolsonaro and was declared as suspect in the case because the cooperated with the prosecution) and was declared ineligible. In a shitshow, the establishment right didn't put forth a good candidate, Bolsonaro, then a whacky low tier congressman most famous by appearing in sensationalist night time talk shows took these votes among with the authoritarian right voters and won against Haddad, the left leaning guy subbing for Lula, but was less popular and charismatic. In the last 4 years every accusation against him dropped and now here we are.

Elections in Brazil are very much safe and unrigged. We use electronic urns that can't be hacked to vote and there has never been proof of any rigging made. We even have a Tribunal that only judges on cases concerning elections.

Unfortunately it is true that some countries in Latin America, especially in Central America, have rigged elections and are under de facto dictatorships, but that really isn't our case. Elections are so important to us that we even make sure that indigenous communities in the middle of the Amazon have access to voting urns