The open source client doesn't mean jack shit dude.
Telegram also has open source client.
Your data lives on their servers not clients and also, even if the server code is open source, there are many ways for a backdoor and violations of privacy in the infrastructure. When you give up your phone number, there is no privacy.
They are super shady, blocked some important security researchers that found a vulnerability from them on all platforms, and they offer no explanation on why using a phone number is MANDATORY for signup.
Just search IBM IoT and look at IBM acquisitions in the last decade.
Everyone "used to work for that company" on the internet. And even if you used to work there it doesn't mean you know anything about their business.
IBM is more of a Holding now. Like Volkswagen. Just because someone works at audi it doesn't mean they know anything about Lamborghini.
SystemD works great, but the corporations and politics behind it will ruin Linux if they fully take over.
They are already optimizing heavily for IoT just because IBM is heavily focused on IoT
I'm using Arch btw