Many .mp4 or .zip files in these groups are actually masked executables. Opening them can lead to your Telegram account being hacked or your device being infected with spyware.
Sharing or seeking out non-consensual private media (Deepfakes or leaks) is a violation of Telegram’s and can lead to a permanent account ban.
Files shared with these types of names are frequently used as "clickbait" to spread malware.