When it comes to comedy, Donald Trump giveth and Donald Trump taketh away.

His chaotic, divisive presidency has been a boon for late-night hosts and “Saturday Night Live” impersonators, who can respond to it off the cuff and in something close to real time.

President Trump is not doing any favors, however, for HBO’s “Veep” and its central character, the former president Selina Meyer (a role for which Julia Louis-Dreyfus has won five consecutive Emmy Awards). The series begins its sixth season on Sunday with its humor as acidic and gleefully foul as ever. But when real life exceeds the show’s most over-the-top imaginings, it also takes some of the life out of the show’s satire. Coherent story lines and parsable dialogue, applied to national politics, feel so 2015.

This may be unfair to “Veep” (it’s more about perception than quality), but it’s hard to ignore. It’s the end phase of a shift that began last season. My colleague James Poniewozik noted then that the show had an “almost reassuring” quality amid the circus atmosphere of the campaign.

No matter how far “Veep” goes in its portrayals of venality, ambition and general cluelessness — in Season 6, Selina, shopping for a legacy, turns an election-monitoring gig into a bribe-a-thon to raise money for her presidential library — its characters acknowledge, at least in passing, that there are rules and norms they are violating. They even show occasional remorse. That’s the reassurance, and it’s a context that’s necessary for the success of the show’s kind of rationally plotted farce. At the moment, though, the show seems to be satirizing a political culture that no longer exists.