I recall that they announced this change. I think they had been getting too much flak for providing screen time and publicity for the loonier sides. Sucks if they have traded one journalistic failure for another.

I can't find the announcement, but https://about.abc.net.au/2017/11/whats-wrong-with-being-fair... is the ABCs take from 2017, and https://independentaustralia.net/politics/politics-display/l... an example of criticism from 2019 that the ABC was still "both-siding".