I kinda found out why numbers keep getting banned.
I have two possible reasons behind banning of numbers. Hopefully Telegram would take action on this.
Telegram Web. - When I log in using the QR code on web.telegram.org, after a few hours my number got banned. I'm using Opera when it happened. However, it wasn't banned when I used Brave.
Any 3rd party Telegram API apps. - Aside from the official Telegram App, I'm also using Nicegram and TG Connect. My number was currently logged in on the official Telegram App, but when I loggeg in using either of the two, my number got banned.
So far those are my observation after I have been in this cycle of banned > appeal > recovered > logging in > banned.
I don't know if you also encounter the same problem. Let me guys know.