WOW, that's really simpler than expected. Sadly, I think most of us will not be able to take advantage of it if using the Eero that is not in bridge ... let's keep this conversation going. Hopefully the dev team picks it up as an enhancement.

This seems like it should not be a hard feature to implement.  A toggle switch to turn it off.  I fully agree that this is unnecessary traffic for those of us on data restrictions.  The data on satellite service is EXPENSIVE!  So every bit that flows through that modem is precious!  

Any progress with this request? On January 1, 2021, Comcast/Xfinity reclassified all of their unlimited plans to limited plans. We do not need euro routers to be using 2 GB of data per month on speed test and other unnecessary downloads. I would like the ability to turn off the speed test. There’s no reason to check out every day. Thank you. 

Everything here is valid- from an ISP standpoint- having tons of Eero devices on a segment of our network choking bandwidth availability is a big concern with scaling with Eero.  Our access points are capable of handling varying amounts of traffic, some only can aggregate 120-150 MBPS for all clients connected.  Being able to turn this off is sort of a make or break issue for us choosing to scale our business with Eero.

amazing that 4 years later, this still is not possible

How is this such an impossible feature to expose? The fact that it is still unimplemented 5 yrs later is beyond ridiculous. The hubris is what bothers me. Why does Eero assume that they know what is best for uses of their hardware. I recently found that the reason so many of my HomeKit devices lose connection is related to the speed test. 
 

Please tell me what is so hard about adding this feature. 
 

AFAIK no other router forces you to run speed tests. Failure to change this will likely encourage me to switch to a better alternative. Cool routers but they have been nothing but a pain the butt for HomeKit. 
 

But what do you expect from AMZN…

Please read to end to fix....disable speed test. I am in IT, but didn't want something too complicated. Tried and loved the Eero. I knew some things would be limited being a residential device. But it had the distance, speed, mesh, simple to use. Had the family, friends, etc buy in to it too. I had the Secure basic (didn't need the VPN, Malwarebytes, etc.) subscription for $29/yr. to block ads, bad sites, etc. Then corporate greed (Amazon) stepped in. Now only $99/yr. for everything you can't choose anything else.

Looking for alternative found NextDNS to do same thing for $20/yr. But in my investigation, open my eyes to the limitations of Eero. Things that are locked down, can't change, or see. Can't monitor each device, just get an overall up/down. You can see blocked items but nothing in detail. Oh, check the logs you say? Even my old Linksys, Netgear, D-Link you could do that, not Eero! You have to call them and stay on the phone with customer service for THEM to check YOUR logs - wth? Enough!

Had PiSense and PiHole in the past. You have to know what your doing, install in virtual machine or separate Pi or old PC, more pain in the butt than it's worth. Needed something in the middle.

Went out and bought Firewalla Purple ($350ish) it's a little pricey but you have full control with ease of app.

And finally, how to block the automatic (can't turn off and have not fixed in 5yrs) speed test.

After installing Firewalla Purple, put Eero in bridge mode. Then it runs a speed test (one last time) and now I can see it, monitor it, and finally BLOCK it. 850MB every day...gone! See screenshots (blocking already hence the unblock).

I also noticed LOTS more stuff. For example how much my "smart" Samsung fridge talks to Samsung. It's a fridge, how much info do you need to send? Goes to find out little, but 62,800 times a day! Not joking about it! I started blocking it 24hrs ago. Check screenshot (Tizen is network adapter for Samsung). Why not turn off Wifi on it, it has a "tablet" screen built in :( and like the weather, time, and other useful stuff. So allow download, block upload. 

Sorry so long but hope it helps.