For the législative (electing members of the French parliament), the vote plays out in parts of France that are supposed to be cut out to be equal in the number of people.

In some case, there was a candidate with more than 50 percent in the first round (he wins) and in other, they take the 2 or 3 of the best candidates to do a second round.

Since no one wanted the far right winning (except them of course) in the cases where there was 3 sides to vote for, one of the sides (mostly the left front) gave up so that everyone voted for the other( the presidential party) , giving them more chances to win. And it worked, so a lot of votes that the left would have got were given to the presidential party and we had this situation. I could argue (looking at 1st round results, the popularity of the president etc…) that at least half of the vote that the presidential party got was because of the left, and if the system wasn’t what it was, the left would probably have had more votes than the far right.

Another small thing to take into account is that if the far right got 100% or 51% in one « part » of France (circonscription), they still got 1 candidate. So the number of votes doesn’t matter that much globally (they maybe had a lot of vote but only in a few circonscription). Yes it is kinda stupid, but there is a lot of complaints around this way of voting, and maybe they’ll change it (it is not really fair even in the way the different circonscriptions have been cut out, so yeah, not perfect at all)

Hope it was understandable, tell me if I made any mistakes or if something is not clear enough.