Onderzeeboot
Ecstatic Orb
I don't really mind the landfall frame on non-landfall permanents, as it still looks good on the "new" cards. The stained glass frame is actually the Dominaria showcase frame, not to be confused with the stained glass planeswalker frame. The adventure frame kinda suck on non-adventure cards, because they left the book background in. Awkward when the text box doesn't actually look like a book itself. Finally, I'm assuming you mean the archive frame from Strixhaven when you say invocation frame (invocations we're used in Amonkhet, this showcase frame included creatures), and I would argue that this frame looks more than fine on creatures as well. There's no particular element in the frame design that screams "I'm a nonpermanent spell" imho.Okay what about the Adventure frame?
(Only cards with Adventure)
Or the Invention frame?
(Only artifacts)
Or the Invocation frame?
(Only instants and sorceries)
Or the Landfall frame?
(Only landfall permanents)
Or the Stained Glass frame?
(Only planeswalkers)
In short, I don't mind when a showcase frame is used for other things than it was originally intended for (as in, which batch of cards is was originally used for), unless the frame was designed with that specific batch in mind. E.g. the enchantment frame exists because there is no easy way to tell something's an enchantment in addition to its normal types, so it would be easy to miss, or how Eldraine's showcase frame fits the shape of the adventure cards' frame and not those of normal cards, or how the Kaladesh showcase frame specifically is colored to invoke the spirit of the old artifact frame, so it looks very off on nonartifacts.