Date & Time: Noticed 3/15/2018, 2:03 PM PST
Frequency: Just once.
World name: Mateus
Character name: Tseren Nahvi
Class/Level: RDM, Lv70
Party or solo: Party
Area and coordinates: Forbidden Land, Eureka

Steps:
1. I had attained Lv6 in Eureka.
2. Was not in Kugane or Eureka during the maintenance.
3. Have not AFK'd or logged out in Eureka.
4. Went back into Eureka and found out that I was reduced to lv3.