I think it is the other site that was arrested. This is posted on maplestage's site
"Note: Maplestage™ has no relations with 8maple.ru
We were made aware of the 8maple.ru situation hours after we shut down our services. Due to the impeccable timing, we feel the need to clarify that maplestage.com has no relations with the other entity. They started using our Chinese branding (楓林網) sometime after we gained popularity in the early years. We asked them to stop using our name countless times but did not get any meaningful response. We did trademark the English name "Maplestage". But because we are US-based, we could not find any reasonable way to protect the Chinese counterpart. In the end we had to give up trying.
Maplestage.com is shutting down now primarily due to the ongoing Pandemic. This global crisis had made our already small Ad revenue stream non-existent."
(Plus, I doubt the authorities would just let them post a note on their site before arresting them. Just a thought.)