This question of how to include text that will appear in html but not pdf has been answered twice (LaTeX multicolumn block in Pandoc markdown and Pandoc markdown: Omit text
I found an answer: add the -native_divs
extension.
This way:
$ pandoc essai.md --from=markdown-markdown_in_html_blocks-native_divs -t latex
My text.
other text
My understanding is that pandoc has started interpreting If someone has a better solution or a better explanation, please let me know. is added in html. This behaviour needs to be deactivated in order to obtain the desired effect.