So your client wants to add a really cool widget to their site.
Previous meetings you’ve meticulously explained the course of the current development, and now they’ve arrived with a car full of clowns. The client doesn’t need vomit inducing adverts for their site visitors (but hey, what’s .00067c of income! that’s extra cash!). It’s great ideas like this that cause churn.
Maybe they’ve overlooked the 77823647823 hours you’ve put into carefully thinking about their needs, their visitors needs, and technical capabilities? It doesn’t matter now, because their website is going to look like a lawsuit for a lack of epilepsy warnings.
But hey, they say it works for other people (maybe they are an affiliate of the company trying to sell their crappy codebase?). Just be prepared for your lovely project files to be hacked to death to shoehorn this crap in there.