This strip is by Dino, whose main Journal de Spirou series is Tash & Trash. (There’s no entry for this Dino in either the Lambiek Comiclopedia or the Bedetheque, and the author’s official site appears to be down. The best I can find is an Instagram page.)
Julien Mariolle’s main series in the Journal was Yul et sa Clique, but he hasn’t been in the magazine much lately.
Have to admit I was a bit confused by this strip until I realized that the guy in the helmet is not Spirou… This episode is by Nykko & Bannister, who respectively write and illustrate Les Enfants d’Ailleurs (published in English as The Elsewhere Chronicles). Bannister was previously featured here with an X75 strip.
Steve Baker’s main contribution to the Journal de Spirou is the series La Vie en slip (“Life Is Briefs”), a gag comic about three friends, influenced by Calvin & Hobbes.
This episode is by Christophe Bataillon, a French artist who’s worked for a number of comics magazines. In the Journal de Spirou, he usually does gag cartoons and quiz illustrations.
Berth mainly draws gag cartoons for the editorial pages, in particular under the title Le XXIe siècle est parmi nous (“The 21st Century Is Upon Us”).