Is all software developed for every democratic government open source? Weird take to call it illegal. They only got this system up a couple years ago, and they've been dealing with an invasion for the last 2 years.
All software running on citizen devices should be open source in a democracy. As they should have a noscript/basic (x)html portal, if reasonable, to lower the technical exit cost of any "app platform" and to provide a fair, low technical cost, and nearly equilavent access to any alternative platforms past present and future.
"The software industry" is full of scammers (planned obsolescence, etc). It is very hard for govs (democratic) to stay clean here.
EU started to regulate Big Tech, it is only the beginning.
If there's no law against it, then it's legal.
Being a democracy has nothing to do with it. If you're an adult, you should learn the basics of law, because the law applies to you anyway.