Blizzard has replied on the forums about players concerned with a recent string change with the Pet Battle Bonus Event. The change represents only a string fix based on the updates to Pet Battle experience that happened in 9.1.5.
This is simply updating the text to reflect the exp changes made in 9.1.5. Those changes weren’t a nerf to the bonus event, but rather a buff to xp earned outside the bonus event. There are currently no further xp changes planned for Dragonflight.