When viewing a contact card of a phone number not registered on Telegram, you see the name and profile photo of your account.
You see a wrong preview, containing your profile name and your photo.
The app shows actual contact name with no photo.
This issue does not affect your privacy and security, happens locally — on your device only — and visible only to you. Some users were sharing such contacts as a prank to make you believe they knew your phone number. Don't worry — they simply see their own number there, only you can see yours.
Telegram Android 8.2.1 (24627), Xiaomi Redmi Note 4, 11 R? (30)