I had this on my old Surface Book 3 but that had all sorts of problems so I put it down to that. However I have now got a new Surface Pro 8 and I am seeing this exact same behaviour. I use Edge as my main browser and at completely random intervals it will suddenly display that ERR_NETWORK_IO_SUSPENDED error in the browser instead of loading pages. Then after a few minutes it goes back to normal.
Interestingly I've noticed that new-style apps like Settings and Microsoft Store do not load for as long as this persists - if you launch them they just open a blank window with the app icon in the middle and stay stuck like that until the browser returns to normal.
Definitely something very weird going on with Windows. Like others I'd say this started (on my old device) early in 2022, roughly.
Microsoft need to address this with an update, urgently! Is anyone from Microsoft even looking at this or going to reply to help us?