Yeah, I've never even seem a power leveling ban. What's even the title for the ban? I didn't know they banned people for buying power leveling services, how do they detect that lol.
A new IP constantly logging in and doing one continuous activity, then logging off and it returning to the previous (owners) IP address. This along with the passwords changing for the duration of the service, as it will line up with the suspicious IP behaviour.
The bans are for 'RWT Major' currently. I've not seen a ton of these, but as of recently I know of at least three (all on ironmen). As mentioned above, a lot of these situations get handled privately by the providers, for obvious reasons.
It's safe. Jagex do have False Detections though, which is around 1% for us. But overall it's very safe. After appealing a ban it's usually quashed anyway. I would say it's simply scare tactics and some people are falling for it and others can see through the ficade.
I never had issues with multiple accounts and powerleveling before. It’s just since I’ve been back that a lot of people have been mentioning it.
Also, I noticed that all the powerleveling discords that I’ve joined have notes in their rules saying they aren’t responsible for any bans. If you get banned because of the service provider, can’t they just tell you to go screw yourself?

