Thaumaturge
Wandering. Not lost. (He/they)
As you know, in the play test rules background confers the bulk of a character's skills, some proficiencies, and a trait. You are using background to be something much weaker than that. I too have been a student, a father, a gamer, a writer, but none of that is serving the mechanical function that we are discussing.
I can certainly understand that perspective.
It might just be cognitive dissonance, wanting previous choices to matter, that tells me my background (we'll say Student) is what gave me the skill sets that I use today. I've just built atop them and refined them with further experience.
Using the Priest in the playtest as an example, the history, insight, and religion proficiencies are something the character has learned to think of as part of his identity. A 15th level Acolyte Wizard would have a love of religious and historical lore that he could, if he were introspective, draw back to his days as an acolyte. The knowledge he gained then was the foundation he built atop as he adventured and learned more. He's gone on and studied as a wizard, but his days as an acolyte set his feet on a path. He doesn't practice as an acolyte to get better at those skills, he lives life and finds pleasure in learning more about the things he already has a strong basis in.
But you are right—the Temple Services trait makes it sound like the character is currently a part of the temple. I could certainly work with that with characters to make it sort of like a professor emeritus status, but that isn't how it reads at first blush.
Thaumaturge.