Transavia states roughly the same as KLM I would say:
https://www.transavia.com/help/en-uk...-much-to-bring

So one trolley or bag for the bin and one small bag that should fit under your seat. I travelled 2-3 times with them last 1.5 year and never had my bags weighted. They do allow a max of 70 trolley's on board though and once I saw them counting (I was lucky enough to keep mine). So maybe the message is that if you want to be sure you have your hand luggage on board, it should not be bigger as 40-30-20.

This all unless Transavia changed their rules and the website is not yet updated.