Casting the Lumos spell while standing beside the tapestries in this room will cause them to change in appearance, revealing a secret werewolf-related story.

Source: https://gamerant.com/hogwarts-legacy-where-find-werewolf-tapestry-room-location/

However, it would seem that the facial features temporarily morph back into the ones initially picked by the player whenever they cast the Lumos spell, implying the existence of an animation bug.

Source: https://gamerant.com/hogwarts-legacy-bug-player-model/

There is a moth sitting on the stand, cast Lumos to carry the moth with you back to the painting.

Source: https://screenrant.com/hogwarts-legacy-library-annex-field-guide-page-locations/