[Vuejs]-VueJs + BootstrapVue: Table delete items only on first page

That’s because you’re using the index from the scoped slot.
The index will be based the displayed rows, and not the actual index of the item in the array provided to the items prop.

This is described on the docs down in the notes under the Scoped field slots section.

index will not always be the actual row’s index number, as it is computed after filtering, sorting and pagination have been applied to the original table data. The index value will refer to the displayed row number. This number will align with the indexes from the optional v-model bound variable.

I would suggest either using a unique identifier from your object if you have one, or using the reference to remove it.