The function you pass to startTransition must be synchronous. React immediately executes this function, marking all state updates that happen while it executes as Transitions. If you try to perform more state updates later (for example, in a timeout), they won’t be marked as Transitions.
Summary
Since this change: https://github.com/facebook/react/blob/main/CHANGELOG-canary.md#october-5-2023-1830-canary-546178f91-20231005
The line
is no longer true.
Page
https://19.react.dev/reference/react/useTransition
Details
No response