This is standard perpetual licensing seen across many software.
One off payment = you get a perpetual license for the major version of the software including all patches for it.
Subscription = you pay a smaller fee than the one off payment per annum. You get all updates and patches. But when you stop paying, you don’t get anymore updates or patches and you can lose access to the software.
I’ve read it a few times over the years. Maybe I keep reading people say the same misinformation. I suppose without root we’ll never know.
Your anecdotal evidence could just be that you’ve ruined your profile; although of course, you could be entirely correct.
I’ve only used it to remove annoying apps, e.g. Facebook. I’ve never gone crazy with it as I don’t care about the manufacturer’s pre-installed apps as they’ve remained silent for me.
I don’t trust Windows Defender at all. I use BitchDefender all of the time. I tried Windows Defender for a year and it didn’t fill me with confidence.
I also upload to virus total anything from an unknown source. I tried to use Intezer as well but I had many problems with my account that I have up on them. For some reason their server didn’t like my account. A brand new account got closed the following day for being inactive for too long. A week later I can reset the password but I can’t log in.