Battleground score earned this season (2) reset to 0

Yestersay, on september 16th 2023, I had a score of 150 (bronze 1) on battleground I earned doring this season (2). Today I talked to the battleground NPC, and it showed me the season 1 summery, and then reset my battle ground score to 0.
Needless to say I already saw it when I actually started playing the season 2 of battleground.

Important detail: I recently reached lvl 800 and changed difficulty to inferno 1. Maybe this is the reason it happened?

Devices details: I usually use samsung galaxy tablet S8+ to play the game, the bug accured when I opened game from my smartphone (samsung galaxy s9+).

Please help me to solve this issue!

Yes, it’s the reason.

The battleground leaderboards are separated into the Hell players and the Inferno players. When you’re paragon 799 and have killed H8 Phangwrth and are offered the upgrade to Inferno, there’s a short tutorial about what changes this will make. This is included in that tutorial.

This is not a bug. You start from scratch in the Inferno leagues.