The majority of those 8% intend to vote for Lula on the second round
Source?
both Flavio and Lula are tied on the polls
the round-one polls had Lula leading Flávio by 3 points. the result was instead Flávio leading Lula by 2 points. That's a big miss.
WTF does "more right-wing" than alt-right
I'm not good at Brazillian politics either, but I'm going to research the entire makeup of the 8%:

- Cury's (2.86%) is the only one I'm not sure of. On one hand his party's ideology is moderate "Labourism", on the other hand:
Thaise Lima, a 41-year-old lawyer on her way to vote in Sao Paulo, said her main goal was to get Lula's Workers' Party out of office. "I don't think Flavio is the best candidate, but I might decide to vote for him in the next few minutes," she said, adding that she wished psychiatrist and author Augusto Cury were a more viable candidate.
- Renan Santos (2.24%), Missão: National liberalism, technocapitalism, bukelism, "The Feindstrafrecht says that certain people, as enemies of the society (or the state), do not deserve the protections of the civil or penal law." At least they support sustainability and infrastructure. Santos alleged a "wave" of neurotypical individuals falsely claiming to be autistic to obtain benefits and neurotypivestigated an actress.
- Ronaldo Caiado (2.18%): For some reason "Social Democra-" means economic neoliberalism in Brazil apparently. Party ideology mostly known for pragmatism: "We are neither a right-wing party nor a left-wing nor a centrist party." (?) Caiado is a right-winger known for criticizing Lula and leading opposition to land reform, seems to have similar campaign on crime as Flávio Bolsonaro.
- Romeu Zema (0.27%) in 2023 implied South and Southwest Brazil separatism to the great horror of everyone and Bolsonaro. In 2020, he said "We need to have tools that curb what we might call a natural instinct of human beings" to promote a support program for domestic violence survivors. In May argued for child labor (under 16).
- Samara Martins (0.10%) is left socialist.
- Hertz Dias (0.04%), Fourth International.
- Clariano Barão (0.03%), Christian Democracy party, paternalistic conservatism. Like the German CDU so I'll concede this isn't more right-wing.
- Edmilson Costa (0.02%), communist.
- Wilson Grassi (0.01%), single issue anti-abortion "Woman's Party" known for failing to meet state quota of women candidates in 2017.
- Rui Costa Pimenta (0.01%), of dissident Trotskyists party that praised Taliban and al-Qaeda for triumph "over American imperialism", opposes "gender ideology".
Excluding Cury and Barão, I count 4.71% right-wing against just 0.16% Lula-ish, or against 0.19% if we include Barão in the latter count, or against 3.05% even if we include Cury in the latter (which I quite doubt we can). If we add these numbers to the first-round results of Flávlo vs. Lula, Flávlo'd have a 6-point, 6-point, or 4-point lead.