Please don't take this as being supportive/empathetic/understanding of the shift of some brazilians into supporting the fascist scumbag and his cronies - but just wanted to try and contribute a little to the context that lead to this point!
Think it's important to note that Lula's party and Lula himself (along with Dilma) are also very deeply unpopular with those that don't support them and that includes with some people who have voted for him/them in the past or at least tend to vote for left parties. As with Bolsonaro, if you aren't a supporter of the man there's not many who are ambivalent or indifferent - they're deeply hated.
On Lula there can be a perception (sometimes factual, but also often a result of conspiracies/stitch ups) that he and PT (his party) are loose or even corrupt with public funds, rife with cronyism, friends to dictators (Chavez/Maduro) & want venezuela 2.0 and are weak on crime ('they care more about the wellbeing of one's armed robber than the victim').
Understandably the majority of media noise that tends to reach us as an international audience is framed around Bolsonaro the dangerous fascist with an emphasis on the depressing number of Brazilians who will vote for him - but the thing that's often absent is that PT put up a guy who (rightly or wrongly, and entirely unrelated to his previous tenure) is tarnished by his spell in prison and with the way much of his base were still unequivocally supportive of Lula in spite of the conviction (before it was overturned) - ie a sort of cult of personality 'he may well be guilty, but I don't care' vibe. It's not an exact analogue - but imagine if Labour had Blair as leader in a general election sometime from 2010-15 - there'd be a view of the party and him being self indulgent while a clear and dangerous enemy needs beating.
What I'm getting at is there's a lot of push levers away from PT and Lula himself, which explains a portion of the vote Bolsonaro received, alongside an unprecedented level of complex and costly misinformation (mostly online) campaigns - lots of votes being cast based on 'feelings' and motivated by opposition to the opponent rather than a particular love of the opponent. Again, if there's a UK analogue, I'm thinking the brexit vote and former/current Labour voters who voted in line with the leave campaign (figureheaded by politicians of seemingly rival factions and not-very-compatible politics).
All this is to add to some of the chat before about why some seemingly surprising people feature among Bolsonaro's supporters (alongside the more obvious full blooded fascist scum, religious fundamentalists, the ultra rich who've been bought, militaristic senior police, ex-military/supporters from dictatorship era etc).
My view is that there are some understandable reservations/issues that some have with Lula (especially internationally, just look at his anachronistic views on Ukraine to see proof that he's an old man who can get a little lost in entrenched simplistic ideological views from the past, despite new information - although I'm confident he'll come round on this quickly). And I'd add that since the majority of us western anti fascists (incl most media, who even if right leaning tend to be pro democracy) want Bolsonaro out desperately, there hasn't been a great amount of listening or learning about why this situation has become possible in spite of brazil's independent democratic institutions and their checks & balances. But absolutely none of those reasons are significant enough a justification to opt to vote for the fascists (worse still, cheerleading for them - looking at you Rebecca Tavares... hope you had a horrible Sunday night). That goes double for the second round of an election. If ever there was a time to 'hold your nose and vote' for the person you passionately dislike, it's when the opponent is as up front a fascist as you can see in the democratic world.
