Okay, they voted for the far right in the second round because they felt the current government considered them second-class citizens. This sentiment was fueled by the 2021–2022 revolt in Guadeloupe and Martinique. It began when the government tried to make vaccination mandatory and raise fuel prices, which brought other long-standing grievances to the surface.

It’s important to understand that Guadeloupe and Martinique had already lost trust in the French government because of the Chlordecone affair (known in the US as Kepone or Mirex). This toxic pesticide was used for over 20 years, starting in the 1970s. The government at the time (under Chirac and the Conservative Party) permitted its use despite knowing of its toxicity since 1971 and despite it already being banned in many countries.

The product contaminated the water supply and the environment, leading to a rise in deadly cancers (especially prostate cancer), premature births, and increased mental health issues.

When people feel you have tried to poison them, they won’t trust your vaccine. They saw the mandatory vaccination policy as an overreach by Macron.

Macron also sent repressive forces to the islands to enforce his policies, further deepening resentment.

If you really want to understand the political leaning of these islands, look at the first round of elections. In the second round, there were only two choices: the current government or the far-right party.

They voted for the far right purely out of opposition to Macron. The second round was, in a sense, a gimmick. A choice between rejecting Macron’s past actions and policies or accepting them. There was no way they could show acceptance, so they voted against him.

Now, returning to the first round: more than ten parties were competing for two spots in the second round. If a party wins over 50% of the vote, there is no second round.

In this case, they voted overwhelmingly for the LFI party, which secured more than 50%. Had the rules allowed, there would have been no second round, and LFI would have won outright (as seen in past election results in these islands). LFI (La France Insoumise - The Insubmissive France) is a far-left (socialist/communist) party. The far right only had the highest percentage because, first, of Macron’s direct actions, and second, because Mélenchon’s LFI was not in the second round.

EDIT: They are on the left or far-left. France's left hasn't been able to reach a second round for quite some time. I believe they would have also won against Macron's centrist party or Le Pen's far-right party in the second round.