fix: revert buggy reactive vars optimization

[dummdidumm]

Reverts #7942
Fixes #8374

FYI @tanhauhau I'm proposing to revert the change - the optimization seems small in comparison to the potential maintenance overhead (and the bug) it introduces. If you disagree, you're welcome to propose a different PR which fixes #8374 instead. I'll merge this later this week if no objections.

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