The only bit of information this leaks to the recipient is that you're a Telegram user and opted into this feature. Otherwise, it's no different to someone rand

The only bit of information this leaks to the recipient is that you're a Telegram user and opted into this feature. Otherwise, it's no different to someone randomly typing your phone number in and texting you? What is the risk exactly? If someone wanted to spam/harass/etc people, he can do that by just mashing 10 random digits in the dialler UI and repeat until he gets a successful call/text through, or lookup their country's number range allocations to narrow down to a specific carrier/etc.