Why legitimate accounts get restricted
Telegram does not publish its anti-spam rules, so nobody outside Telegram can say exactly why one account was limited. These are the situations affected users report most often. Use them to describe your own case accurately, not as a script.
Messaging, inviting or forwarding links to many accounts that have not saved your number is a common trigger for a SpamBot limit, even when the content is legitimate community or group admin work.
A number that was recently issued, previously used by someone else, or provided by a virtual/VoIP carrier can be restricted at sign-up. Say when you got the number if you know it.
Logging in from shared VPN or datacenter IP addresses, or switching countries quickly, can look like automated traffic. If you used a VPN, say so plainly.
Support teams receive many identical forum templates. A short message with facts from your own account (when it was created, what you were doing, what changed) is easier to review.