PvP highest Tier went down by a star

When i played Crystalline Conflict i lost a star in "Highest Tier" somehow.

Date & Time: 21.04.2022 1:30am to 4:30am (GMT) and ~7PM (GMT)
Frequency: 2 times so far i noticed
World name: Lich
Character name: Hideko Tenshi@Lich
Class/Level: MCH/81-82
Party or solo: Solo
Area and coordinates: Wolves' Den Pier
Steps:
1. Ranking up in Crystalline Conflict
2. Ranking down in Crystalline Conflict.
3. And ranking up again.

https://cdn.discordapp.com/attachmen...25/unknown.png
https://cdn.discordapp.com/attachmen...90/unknown.png
https://cdn.discordapp.com/attachmen...42/unknown.png

Edit: It went down even more? Isn't it supposed to be the "highest rank" i reached in this season?