OTP anti-fraud regulation is aimed at preventing the scammers from abusing the system by making unlimited OTP requests to authorise into Driver and Customer apps.
The following OTP request rules apply:
5 OTP per account Id per day (from one user account - any profile: customer, driver, user)
or
5 OTP per device Id per day (from one device)
or
5 OTP per device Id and Identity per day (up to 5 phone numbers per device)
This means that:
a user can make a maximum of 5 OTP requests in 24 hours from 1 device and/or for 1 phone number. If the limit is exceeded, the user is blocked for 24 hours from the moment of the last OTP request.
a user can log in with a maximum of 5 numbers on 1 device in 24 hours. If the limit is exceeded, the user is blocked for 24 hours from the moment of the last login (on the 6th number).
In case a user is blacklisted due to violation of OTP limits the following error is generated:

A user will be automatically whitelisted within 24 hours from the last OTP request.
Consult the post on Driver and customer "cool down" for details on the limit of cancellations for drivers and customers.