history.push sometimes triggers refresh sometimes not - reactjs

Question

Using React 17 and React Router Dom 5.2 I've encountered a strange phenomenon.
In a simply CRUD application, there is a component for listing up all items, one for creating, and one for editing.
A little bit simplified, the code looks like this:
parent:
<Switch>
<Route path="/item/create" component={ItemCreatePage}></Route>
<Route path="/item/:itemId" component={ItemEditPage}></Route>
<Route path="/item" component={ItemList}></Route>
</Switch>
create:
import React from "react"
import { useHistory } from "react-router-dom"
import { ItemCreateOrEditComponent } from "./item-create-and-edit"
import { CreateItemInput, useCreateItemMutation } from "/types"
export const ItemCreatePage: React.FC = () => {
const history = useHistory()
const [createItemMutation] = useCreateItemMutation()
async function createItem(itemToSave: CreateItemInput) {
await createItemMutation({ variables: { data: itemToSave } })
history.push(`/item`)
}
return <ItemCreateOrEditComponent createOrEdit="create" saveFunction={createItem}></ItemCreateOrEditComponent>
}
edit:
import React, { useState } from "react"
import { RouteComponentProps, useHistory } from "react-router-dom"
import { ItemCreateOrEditComponent } from "../../../components/form/item-create-and-edit"
import { UpdateItemInput, useItemQuery, useUpdateItemMutation } from "/types"
type Props = RouteComponentProps<{ itemId: string }>
export const ItemEditPage: React.FC<Props> = (props) => {
const itemId = props.match.params.itemId
const [item, setItem] = useState<UpdateItemInput | undefined>(undefined)
const { data } = useItemQuery({ variables: { id: itemId } })
const history = useHistory()
const [updateItemMutation] = useUpdateItemMutation()
React.useEffect(() => {
if (data?.item) {
setItem(data.item)
}
}, [data])
async function updateItem(itemToSave: UpdateItemInput) {
await updateItemMutation({ variables: { data: itemToSave, }, })
history.push(`/item`)
}
return <ItemCreateOrEditComponent inputItem={item} createOrEdit="edit" saveFunction={updateItem}></ItemCreateOrEditComponent>
}
So, create and edit do basically the same things: Use ItemCreateOrEditComponent, trigger a DB function for saving (Apollo GraphQL in this case, but doesn't matter) and then go back to the list: history.push("/item").
However, the strange thing is: After editing, the list is refreshed with the updated item. After creating, the list is not updated.
It's not a race condition, adding a few seconds of timeout before history.push("/item") doesn't change anything.
The only differences between creating and editing I see are
For editing, the data gets fetched from the back-end
For editing, there is a URL prop containing the items id
I cannot image why these two things should have any impact on whether a refresh is triggered or not.
Edit:
ItemCreateOrEditComponent provides a form, does some validation and transformation, and then finally calls this.props.saveFunction(this.state.item) in the exact same way both for edit and create. And till it comes to history.push I cannot see any difference in behavior there.