This looks a lot like 33mail (https://33mail.com/) which I've been using pretty happily for 4-5 years now (and paying I think $10-15 a year for, so a lot less than this on a per month basis, but they're not strictly unlimited)
With Idbloc (and apple sign in) the address is completely random and untraceable, and it’s impossible to tell which addresses belong to which users.