I'm a little bit confused to why "de" is added in:
Éprouver de la joie.
I thought "éprouver" is systematically followed by "de" but in this example (from Collins dictionary), we don't add it:
Qu'est-ce que tu éprouves à ce moment-là?
Not
Qu’est-ce que tu en éprouves ?Or
De quoi est-ce que tu éprouves?
I also thought that "Joie" is generally preceded by "de" but in a lot of examples I found online, it's only preceded by "la":
Ces réunions se passent toujours dans la joie.