I've been talking to Siri since it launched and never experienced anything like this.
In fact, I've had many(!) moments where I felt it would have helped my experience if it was able and allowed to suggest products and services to me. But, as always, it's only ever able to talk about trivia-esque facts and then "search the web for that" for everything else.
The best Siri has done with pairing my data with ads is sometimes suggesting apps from businesses when I travel around, based on my location. But I feel that's about it (and it only works on occasion). It's great when it works as it saves me a little time finding the app myself. But, of course, that's something I've enabled and not happening without my permission
With that in mind, I can entertain that there's some truth to what plaintiffs are alleging. Sure, I don't know the exact details, but I know that some apps and tech corporations have been doing something like that. So why not also Apple and its advertisers? It's not impossible just because Apple is branding itself and selling many of their products on "privacy".
But I also have to employ some critical thinking and suggest that getting ads for (generic, mainstream, hugely popular) clothing and fast-food brands, like Nike and Olive Garden, will happen to most of us a couple times a year.
The same goes for surgical treatments: millions of people are researching all kinds of surgeries every day. I've never had any elective surgeries, and don't look for beauty and health topics online or in apps. But have still gotten many ads for surgeries and various clinics.
Furthermore, all websites and many apps are constantly trying to build a "profile" on users to serve them ads, even the ones that aren't logged in, haven't used the site before, etc.: With just a few interactions, your IP address, and maybe gps location, they can quite accurately make some very good guesses about who you are and what you want to buy.
Not super specific, revealing guesses that would identify any particular individual. But something like "it's March and users in this location, who are online at this hour, probably belong to this age range, who have clicked these things on the site, usually shop for these mainstream clothing brands or look up locations of these fast-food chains. Let's send some New Balance and Subway ads their way. If they don't click that then they belong to a different demographic and want Urban Armour and McDonald's".
I'm undecided.
But in the meantime, I'll keep using Siri every day, constantly berating and belittling it for its incompetency while "share audio recordings with Apple to help make Siri better" is confidently toggled on, thank you very much! 😏