Can't say for sure but I think there's sth wrong with Redstone update.
There is a structure (see screenshots), in the left there's a Cmd Block that has /setblock … air destroy to destroy the Comparitor at right.
What it is supposed to be that, the Redstone Torch is supposed to be relit when the Comparitor is destroyed and that's what happens in 1.21.4. In 1.21.5 however the Torch cannot detect the Redstone update for reasons I do not clear (…11.19.38.png).
The save is as well attached below.
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