Seeing that WhatsApp is not prohibited in Russia is a big concern of itself. This country has a law that requires you to pass ‘master key’ (or a backdoor, if you read between the lines) to special agency, or be banned by all ISPs. When my friend researched the topic, some interesting guys told him few years ago that whatsapp is a no-brainer for them to read, but tg+secret is opaque. Subsequent events shown that it was probably true.

All this is full of false negatives and positives, but concerns too much to ignore, if you’re after secrecy that puts your welfare at stake. If you just hide your pics from a corporate big brother, I admit that whatsapp and regular tg chats may have different weights on scales.