When I press on some message to forward it, it shows me Random usernames of contacts I don’t know. And it even shows some Mobile Numbers I don’t know. For example, one number starts with +964 that’s Iraq. I’m from Europe tho. These contacts and numbers are from all over the place.
Edit: This only happens on Signal Desktop. If I try to forward a message on Android it only shows my Contacts. And none of these unkown ones.
I see your point and don’t negate such possibility. Although the black box nature of proprietary dependencies in vanilla Signal means an inclusion of potential trojan spyware. Speaking of the need for app lock, as an alternative solution, you can create a separate profile for Signal to have a dedicated PIN. But afaik only GrapheneOS allows notification relaying to main profile. LineageOS on the other hand has a feature called AppLocker. If you intentionally lend your device to kids, Android has a feature called app pinning.