"Lady Hyacinth McCall brought all her treasures to a reef
Where she only wore a smile
Plus two feathers and a leaf
So no one tried to rob her 'cause she barely wore a stitch
For when you're in your birthday suit
There ain't much there to show you're rich"
Wrong, sleazebag. Completely out of character for the wholesome Mary Poppins. Walt would have never allowed it and Julie Andrews did nothing of the sort in the original.
'Cover is not the Book' is in the style of classic Music Hall songs, which often were vaguely bawdy and humorous. It was considered a lower class form of entertainment, like vaudeville in the USA. People would drink and smoke in music halls and be generally rowdy. Part of the joke was that Royal Doulton is posh and Music Halls are definitely not, so a Royal Doulton Music Hall is the type of contradictory humour Mary Poppins enjoys. The entire song is vaguely suggestive, but in a way that would completely go over kids' heads.
If you ever see the first Mary Poppins movie, you'll find out that there is at no time any vaguely suggestive lyrics or dialogue. And Lyn Manuel put his hat over his crotch with a dumb grin on his face for God's sake. Go watch "Chicago" if you want that.