Yes, they're surely not getting rich, but it's commendable that except from selling their own merch, they do not go the raycon/nordvpn/brilliant/younameit route. With Adsense alone I'm pretty sure this would not be sustainable, but they have a pretty successful Patreon.
Not quite true, they got in trouble recently for running a Nintendo ad without properly labelling it (until it was pointed out, the video is fixed now): https://youtube.com/watch?v=V10wHzV5zp0
Screenshot of original video: https://www.resetera.com/threads/digital-foundry-posts-an-ad...
It is a bit shameful that games journalists didn't cover this at all - seems almost like an omertà. Even assuming the mislabelling was an honest mistake, running the ad in the first place makes me trust them less. Worse, I used their videos when deciding to buy a Switch 2! I would have been much more skeptical (likely ignored them entirely) if I had known they were taking money from Nintendo.
They labeled it as "sponsored" when it should have said "ad". I mean yeah, it's weird to simply repost a straight ad on the main channel, but at least that's clearer than integrating it into their own content. The description also always made clear that it's content provided by Nintendo.
If you believe that this influences their view of the Switch2, then by all means, get your information elsewhere. From what I've seen, they've actually been more critical of Switch2 than most other outlets, highlighting the issues with the blurry screen and also the rather lackluster line-up from third parties, mainly because Nintendo is intentionally stingy with dev units.