[OGMcOW2]

My very superficial understanding is that the aether was a fictional - fluid and solid - physical medium that was supposed to model behavior but created more problems.

Quantum fields are mathematical representations that model physical behavior (including the probabilities inherent in quantum mechanics).

Aether, in my interpretation, was a "thing", and quantum fields are just values that describe properties of things.

Depending on how crazy you wanna go, that does of course also make them things, and you could also look at the aether as a mathematical abstraction, but afaik, quantum fields work ridiculously well and are a solid theory, while aether - despite maybe being cutting edge at its time - is more one of the homeopathies of physics.

That said, I'm sure if looked over by someone who actually studied QT/QM/QFT/GR/SR, they'd find what I wrote to be comically primitive and inaccurate :)

edit: punctuation