Blizzard is a different company now. As much as absolutely possible is automated when before you had real people. They seem to have changed the length of the bans as well. Permanent used to be reserved for gold sellers and exploiting the economy. Bans for botting were short.

I feel its now like this:
Player reports -> computer algorithm -> ban -> appeal -> real person

For your ban, I don't see how it was your scarlet monastery boosting. Other players cant see you in there, seems unlikely to be mass reports from it.

Maybe a streamer saw you and had his fans mass report you.