It never was closed source. They simply implemented a feature before uploading the code. Is there a rule to how how many commits need to be made in a time period? No.
> to integrate some cryptocurrency scams into it.
You clearly haven't read enough about why they chose to implement a payment system and why they chose to create their own. There are very good reasons they did both. Don't be salty because they didn't use the one you hold.
> why would I choose a messenger that requires a phone number over another that does not ?
Unless something has changed recently, telegram absolutely required my phone number. Signal is also working on replacing phone numbers with usernames.
> Mainly because the app is more stable and doesn't dictate its philosophy to the user. Proper e2e encryption has tradeoffs. Why shouldn't the user decide for which conversations he is willing to place convenience over security ?
One can't claim to be a secure encrypted chat app but then not enable it by default. It's completely fine to not have encryption, but it's not ok to mislead people into believing it's encrypted all the time.
> Why do you lose your history when you switch between android and ios ?
Mostly because signal doesn't store your messages. There is no central server that has all your info and chat history like telegram does. It makes this harder