Back in 2022 before the first round the highest LFI got in the polls was 18.6%, and they got 21.95% in the actual election, so that’s an underestimate by at least 3%. First round was April 10th, and before April, most polls were giving LFI around 14-15%. Only one pollster (Cluster 17) had given LFI 16% once (so it seemed plausible that this was just an outlier on the high side of things). Have a look for yourself, and look at the numbers at the end of March: https://fr.wikipedia.org/wiki/Liste_de_sondages_sur_l’élection_présidentielle_française_de_2022

Pollsters want to demoralize us. It would be foolish of us to believe them.