OPTIONAL MATCH causing ScanAll on related label

[matea16]

Description
A user on Discord reported using an OPTIONAL MATCH clause on a related label causes a ScanAll operation instead of leveraging existing relationships.

Environment
User tested it on version2.13.0-memgraph2.13.0-lab2.10.0-mage1.13, but it behaves the same on the latest version, 2.16.

Issue
Is this an expected behavior? If not, the fix is needed, if yes, it should be explained and documented

Query plan

[Kevin-Mc-Callister]

Happy to hop on a call to describe the issue better if required :)

I believe what happens is:
On a query, after an optional match, the planner doesn't leverage relationships.