Query `{ exists: true }` not working as expected for empty relationships

Describe the Bug

I'm trying to query only documents that have a tag. Which works fine, but if you add a tag, save the document, then remove the tag and save the document, though the tags are empty in the database it's [] which allows { exists: true } to also work.

I've also tried:
or: [{ tag: { exists: true }}, { tag: {not_equals: [] }}] and { 'tag.title': { exists: true } }

Which doesn't work.

After trying many things, it doesn't seem possible to filter out empty relationships without introducing a new field to track the value on hooks.

Link to the code that reproduces this issue

pnpx create-payload-app@latest -t blank

Reproduction Steps

1. Create a relationship to a tag (hasMany: true).
2. Save the document.
3. Remove the relationship.
4. Save the document.
5. Query with {exists: true}
6. The document will still be returned.

Which area(s) are affected? (Select all that apply)

area: core

Environment Info

Payload: 3.33.0
NodeJS: 22.0
NextJS: 15.3.0