Most email services require a phone number or other email service to sign up if there is anything fishy about your connection/browser (and there can be hundreds of things, even just some strange browser extension installed).
And there are services where you can buy a real temporary 4G/5G number (non-VoIP) for a service for less than a dollar per use. Once a number has been used for that service it still has every other X number of services it can be used for before it’s retired from the pool. But that does add up after a while if you’re making tens of hundreds of thousands of accounts.
Which is also why most services that use phone number for user verification ban VoIP numbers, making this basically useless
Most email services require a phone number or other email service to sign up if there is anything fishy about your connection/browser (and there can be hundreds of things, even just some strange browser extension installed).
And there are services where you can buy a real temporary 4G/5G number (non-VoIP) for a service for less than a dollar per use. Once a number has been used for that service it still has every other X number of services it can be used for before it’s retired from the pool. But that does add up after a while if you’re making tens of hundreds of thousands of accounts.