Google don't release sales numbers so we don't know how many customers come back, however the Pixel 4 line was discontinued less than a year after its release, so we can infer it sold so poorly that Google didn't bother getting more manufactured.
https://www.theverge.com/2020/8/6/21356745/google-pixel-4-xl-discontinued-out-of-stock
On the flip side, if you're suggesting the flagship Pixel phones sell exceptionally well and sales are growing, I'd love to see some support for that as I'm sure it'd surprise everyone. From my understanding, the only Pixel phones that sell decently are the Pixel a line of phones.
You can dismiss what you want (though your reasoning is faulty - you can't just dismiss data because you don't like what it says. You dismiss data in the presence of counter-data), but the article in the OP has been cited in 9to5Google, so seems like they trusted the story enough to post it - and they're certainly not an Apple fan site.