How is measuring or estimating flakiness different than measuring or estimating variance? To me, something that is not flaky never errors for no reason. Somethi

How is measuring or estimating flakiness different than measuring or estimating variance? To me, something that is not flaky never errors for no reason. Something that is flaky errors infrequently and not obviously why. Something that is broken errors a lot. So, to me, flakiness is stochastic variation in a recurring process /with/ some ambiguity about the sources of variation. Flakiness make sense to me as a term for describing variation in relation to cause. That's different than just variance - or maybe flakiness is just variance? I am wondering what the FB framework looks like from a statistical process control POV.