Why does the loss fluctuate sharply when repeats=1?

[gesen2egee]

The gray line represents repeats=1,
the red line represents repeats=100 without changing other settings,
and the blue line represents a different seed.

Why does the gray line show such a significant difference in loss just by adjusting repeats?
Could it still be influenced by ARB? (Approximately 150 images, BS=3), or ramdom sampling between epoch?

[gesen2egee]

repeats=3