Text components nested inside of items inside of text components are not un-flattened to nbt

The specific problem is that data nested inside of text components (i.e item hovers) are not traversed when un-flattening. As a result, text components on item hovers are not un-flattened.

1.21.4 give command:

/give @p minecraft:written_book[minecraft:written_book_content={author:"",title:"",pages:['{"text":"test","hoverEvent":{"action":"show_item","contents":{"id":"minecraft:stone","count":1,"components":{"minecraft:custom_name":"{text:a,underlined:true}"}}}}']}]

See screenshot for how it currently converts to 1.21.7.