I don't think it is because TOS. It would become illegal if they insinuate otherwise (such as stating they will send back your phone once they're done such as in advertising.)
Edit: oh right warranty restrictions/regulations never mind.
This behavior isn’t unique to Google either; Samsung and Apple also engage in similar anti-consumer conduct. For example, in the report about Samsung mentioned earlier, it was found that Samsung requires independent repair stores to disassemble a customer’s product if it has a non-OEM part.
This is one of the many reasons why I advise people never to buy anything directly from Google and always go through a retailer. You basically have zero recourse with Google. If a retailer screws you over you can at least charge back as a last resort but Google has your account hostage. What can you do if they just decide to pull some bullshit like this?
This was the straw that broke yada yada, and why I moved my data out of G a few years ago. If I pulled a cb and they axed my account, I'd lose some gift card info in gPay (that I have backed up in bitwarden), some YT uploads, and the general account, but nothing of value.
But most people aren't in my situation, unfortunately.
I think you got downvoted because the way you said it implies that all 3rd party repair shops are shady. But it's true, that the vast majority of repair shops are shady in places that I have lived.