In Hogwarts Legacy, you have the option of completing side quests to earn different rewards. Below is a guide on the Like a Moth to a Frame side quest!
To obtain this side quest, speak with Lenora in The Library Annex near the Central Hall Floo Flame at Hogwarts. For the first task, you’ll need to discover the painting’s secret. To do this, stand in front of the blank painting and cast the Lumos spell.
Next, you’ll have to find the spot the painting reveals. This spot can be found on the other side of the room to the south. Head down the stairs (a book should be flying overhead) then take a left to find the spot shown in the empty painting. To the left of the statue, you’ll see a moth on the wall. Approach it with the Lumos spell active to retrieve the moth. Return to the empty picture and cast Lumos to reactive the spell to transfer the moth into the painting thus solving the riddle. Before leaving to find Lenora, collect the Field Guide Page next to you!
Afterwards, head up the stairs to the right of the painting and speak with Lenora who is reading a book leaning on the rail over where the painting was to complete the quest. You’ll receive the Cobalt Regalia Appearance as a reward!