The term "false flag" rarely appeared on television news until early 2017 after Donald Trump's election, spiking in January 2021 as his supporters stormed the US Capitol and again in February 2022 as the US accused Russia of preparing to stage false flag attacks to justify its invasion of Ukraine. The term has been trending up again over the last few days as Trump supporters make various accusations relating to the FBI search of Mar-a-Lago and its aftermath.
Interestingly, however, Fox News has actually used the term the least over the past decade.