I would suggest that you need to look at context in order to determine whether a phrase is being used as a dogwhistle.

For example, if someone is also repeating other far-right propaganda (“fracking has solved the oil problem”), what are the chances that their use of this term is in good faith rather than as a dogwhistle?

Hence "by default."

Incidentally, are you claiming one of the above posters here has already included "other far-right propaganda" that tips the scales?

From my perspective, there's been some kind of false-alarm. The danger exists out there, but--unless there's some author reputation I'm unaware of--this isn't it.

Yes, the idea that the problem of “oil” (fossil fuels) has been “solved” by fracking. That’s another right-wing tell, because it ignores the broad environmental destruction caused by the use of fossil fuels and presumes that the only problem with them is scarcity.