Puzzle toys for smart birds

My Quaker parrot is too smart for most toys — figures them out in 5 minutes and then gets bored. What are the most challenging puzzle/foraging toys you've found? I need to keep that big brain occupied!

Quakers

I went through this exact thing with my Quaker parrot Kiwi! It lasted about about a month and then resolved on its own. Hang in there.

My advice would be switching to stainless steel water bowls and changing water twice daily. Went through the same thing with my Quaker parrot last year.