There was absolutely a political agenda in S3. The entire subplot where we find out that Vadic is acting in revenge for the horrific torture she and other Founders endured during the Dominion War, and where we learn the Federation has covered up the true origins of the Section 31 virus, is pretty clearly a story about the ways in which societies that fail to take responsibility for their crimes will suffer blowback in the future.
And on top of that conscious, intentional political agenda, there was a pretty clear reactionary subtext that was probably unintentional: the final arc was about how all those liberal youngsters had been brainwashed by communications technology created by evil foreigners who infiltrated our society, and how it was up to the older generation to save society from those brainwashed youngsters and defeat the evil foreigners. ETA: You could reasonably argue that the subtext of "Vox"/"The Last Generation" was, "Boomers have to save America after Millennials and Zoomers are brainwashed by TikTok."