I work at a ccTLD (.IS), and lately we are seeing a *lot* of new accounts immediately registering multiple domains that all had been registered in the past. I suspect we're not the only ccTLD that sees this.
We know of at least two instances of this being used to take over social media accounts that had e-mails in expired domains set as backup e-mail addresses.
This seems to be organized and well-resourced.
Please double-check you don't use e-mails in any expired domains anywhere.
#InfoSec