What's wrong?

It seems that the problem maybe located in the airing dates.

Based on theTVDB site, this is a Canal+ series. The only dates they appear in the TV program are in 2019, on April 7 : https://playtv.fr/programmes-tv/canal-plus-series/07-04-2019/ and on April 10 : https://playtv.fr/programmes-tv/canal-plus-series/10-04-2019/ (If you click on the emission, no other dates are listed).

The PureBreak site (https://www.purebreak.com/news/bapt-gael-et-les-aventures-de-la-couille-cosmique-la-serie-dejantee-arrive/115167) indicates that the episodes were going to be on a YouTube channel here : https://www.youtube.com/watch?v=35H9HSWxlik&list=PLJ4NSTABOp6XznmvUSnyObIUmTmHml2-E . The currently listed dates are the dates mentionned on YouTube.

So, it seems that this was a webserie that has later been aired on TV.

Before adding the 2nd season, which dates should be used ? The ones on YouTube ? Or the ones on TV ?

which dates should be used ? The ones on YouTube ? Or the ones on TV ?

Always the original (first) air date. So CanalPlay's for the first season (2016-11-28).

Not a problem for Season 1, but for Season 2 I didn't find CanalPlay dates. (I don't have access to it). I have the YouTube dates (2008-04-13... the ones that are listed on TheTVDB) and the Canal+ Series dates (2019-04-07). Should we consider YouTube, even if it's not a TV channel ?

Season 1 fixed. Season 2 added with the earlier know dates.

Should we consider YouTube, even if it's not a TV channel ?

Yes! And, as far as I can tell, the second season was first released on their YT channel.

Also, just for info, I think both seasons first aired on television on Canal+ Décalé starting on 2018-10-28. The Inathèque is a better source for TV air dates.