It's to reflect that Francine Blueblood, the title character of the upcoming episode, is of French descent, hence why all her words that have T and H as their first 2 letters have Z instead (she says "Ze" instead of "The" for example), just like Lady Macaron from the BotBots Netflix series, if you hear her closely. In case you're wondering, "Fête d'anniversaire" means "Birthday Party" in French.
Why's it french?
It's to reflect that Francine Blueblood, the title character of the upcoming episode, is of French descent, hence why all her words that have T and H as their first 2 letters have Z instead (she says "Ze" instead of "The" for example), just like Lady Macaron from the BotBots Netflix series, if you hear her closely.
In case you're wondering, "Fête d'anniversaire" means "Birthday Party" in French.