@artikel10ev basically worse than everthing else...

[Or maybe not. cuz #QQ and #WeChat don't bother to lie into users' faces like @protonmail and #WhatsApp do]

Remember #KerckhoffsPrinciple:
#NotYourPrivateKeys = #NotSecureEncryption!

Also all #Singlevendor and/or #SingleProvider and/or non-#FLOSS solutions are inherently & unfixably bad as well as insecure per design!