According to this post, n8n uses the Formidable module/library for this.
The default limit is (or maybe previously was) supposed to be 200MB. That shouldn’t cause an issue for a 1MB file though.
Regarding the error about “input data” containing “a binary file,” that could be a side-effect of the upload failing to complete.
BTW, I don’t think it is actually part of the problem, but there are accented “special characters” in the form field name Téléversez une image that were substituted in the referenced name T_l_versez_une_image. To eliminate that “name translation” as part of the issue, it would probably be best to remove those characters until everything else is working.