I just read about the harassment you experienced after your telegram was exposed by a person out of nowhere who asked forcibly.
But it is indeed very annoying with a barrage of messages that even become Spam,
such people are usually mentally disturbed and do not think about the actions they make.
Having symptoms of mental mania or hypomania (part of Bipolar Disorder):
In the mania or hypomania phase, a person can experience increased energy, excessive activity, a flight of thoughts, and an urge to overcommunicate.
This can include sending a lot of messages impulsively and without considering the impact on others.My telegram was private, and I didn't factor someone being so annoying.
Lesson learned, btw.
Telegram being the best spam place, I get dozens of messages from strangers, by sending links, files and such.
You need to Hide your telegram username and manage who can send messages, unknown people will automatically be included in the blacklist