When referencing a entity in a lookup field using formulas, the entity is getting treated like it’s part of a “to-many” collection instead of respecting the settings of the lookup field’s source where it’s actually set as a “to-one” relationship.
Is this the expected behavior? Why is the lookup ignoring the settings of it’s source field?
What are your relations, and what are you trying to achieve?
If you have dbs A->B->C and you add a lookup in the A db to get the Cs from the linked Bs then the result will be a collection.
If you add a lookup in the C db to get the A (that is the parent of the linked B) then the result will be a single entity.
If you have dbs A->B-C (or A-B->C) then a lookup in A can get the Cs linked to the linked Bs (or the Cs linked to the linked B). Either way, the result will be a collection.
Adding a lookup in C can get the A linked to the linked B, and the result will be a single entity.
If you have dbs A<-B->C then a lookup in A can get the Cs linked to the linked B (or a lookup in C can get the As linked to the linked B). Either way, the result will be a collection.