Vue version

3.5.20

Link to minimal reproduction

https://gist.github.com/cj1128/49cb31b1f226882d45e9ba7035ea2d93

Steps to reproduce

Run this code under Vue 3.5.20.

import { ref, computed, watchEffect } from "vue"
const T = ref(false)
const A = computed(() => {
 if (T.value) {
 return B.value % 2 === 0 ? 2 : 3
 } else {
 return 1
 }
})
const B = computed(() => {
 return A.value + 1
})
watchEffect(() => {
 console.log("====")
 console.log("A", A.value)
 console.log("B", B.value)
})
setTimeout(() => {
 T.value = true
}, 100)
// output
/*
====
A 1
B 2
====
A 2
B 2
*/

What is expected?

after setting T.value = true, A's value should be 2 and B's value should be 3, or B's value should be always A's value + 1.

What is actually happening?

B's value is stale.

System Info

Any additional comments?

Vue 3.4 will report error Unhandled error during execution of scheduler flush about this case which is better IMO because at least it reminds developers to check the code.