I don’t buy this for one second. The web is well known, and well understood - I’ve never run into anyone, in any age group, with any level of education, who wouldn’t understand what a website is.
Either you’re being overly dramatic and exaggerating here, or you had a very difficult time pronouncing the words you were intending to say.
Now, you would say that these people (35yo) used to use Facebook (and maybe Google meet) and such on desktop. So they should know that many things can be achieved through a browser. But it seems like when thinking about mobile, people think differently. A website that "does something" other than displaying information (which is a weird and blurry definition) must be an app. I'm absolutely sure my friend has never thought it could be possible to use Facebook on through her mobile browser. If you access something with your mobile, it must be through an app.
My friend was trying to explain an app to me. How everyone at his work was amazed at how well it worked compared to their Salesforce solution that they were forced to use.
The app? A website. Not even a web application. It was just a brochure type web catalog that allowed them to show their customer the brands and products they sold.
Other's I've told about ChatGPT or Claude, have trouble finding it. They go into the App Store and search for the apps. They are inundated non-official versions. All with similar titles. Some stop, some install the wrong versions.