Is "established convention" a tautology?

Established convention looks like a tautology to me, though it could be found in many serious sources. Should I avoid it in technical writing and use just convention instead?

The Independent: Green as I am, I learned something new here, something which I suspect would be news to a lot of people, journalists or otherwise: if a reporter has a friendly chat with the Queen, it's a matter of established convention that her remarks remain private.

The Guardian: My aim is to turn established conventions on their heads.

The New York Times: However, when it comes to connected services, there are no established conventions.

Solution 1:

No, I would not consider established convention a tautology. From Lexido:

tautology: The saying of the same thing twice in different words, generally considered to be a fault of style (e.g., they arrived one after the other in succession).

Established convention doesn't say the same thing in different words. I would say though that established is superfluous. From Lexico:

superfluous: Unnecessary, especially through being more than enough.