No, it is not a bug!

We have improved the star display criteria in your profile to provide a clearer view of your progress.

Previously, stars earned from both Normal and Extreme Levels were combined.

This caused confusion as players who cleared all levels with 3 stars would see a total count exceeding three times the maximum level.

To resolve this, starting from the 26.02.19.00 update, only stars earned in Normal levels will be reflected in your profile. Please note that this change applies to all players.