This still has the time traveller doing the destructive thing using the made-up physics of the time machine that causes the doom. The idea from OP is a much more magical one where the impossibility has always been present but things were working fine until someone found out about it, even though no new physical action that could plausibly cause the destruction is involved with the finding out.
Back to the future, doc brown saying a time paradox will destroy the universe, even though there’s no clear reason why that would be the result?
This still has the time traveller doing the destructive thing using the made-up physics of the time machine that causes the doom. The idea from OP is a much more magical one where the impossibility has always been present but things were working fine until someone found out about it, even though no new physical action that could plausibly cause the destruction is involved with the finding out.
Big bird thinking he won’t get any presents on christmas because he realized he can’t figure out how Santa gets down the chimney?