Are you 100% sure of this?
Because that is not the experience of many users since Telegram started charging for SMS verification in some countries.
Many users are reporting that when they try to log into their Telegram account on a new phone, they are prompted to pay for SMS verification. They are not sent the verification code on other devices where they are already logged in. Meaning that even if they are already logged in on other devices, Telegram insists on SMS verification, and that they pay for it.
Even people who have 2FA enabled with an email address and password on Telegram, will be prompted to verify their account via SMS despite being logged in on other devices.
Before when you logged in on a new phone, Telegram would send you a code via SMS, and simultaneously send that same code on Telegram to all the devices where you are already logged in. Since Telegram started charging for SMS verification, that is not the case anymore.