Telegram anti-spam systems can automatically flag your account for spamming if it detects suspicious activities. It can be related to using a banned IP, spreading illegal content in public groups, compromised accounts, reported for spamming, and sending multiple private messages within a short time.
You can email Telegram support via email firstname.lastname@example.org or email@example.com and briefly explain your issues. Remember to include your phone number.
If you are not able to get your account back, consider alternatives.