Why my aquascape shrimps died

Yesterday on around 5 pm I put my two of 10 g aquascape outdoor, my intention is so I don’t have to use LED light during the day. Right at the next morning on one tank, many of my shrimps died, but the tank full of red cherry shrimps I just noticed one red shrimp died.

Additional information:
Since it’s outside I can do big water change on both, and I did right after I moved them. Also there were rain after I did water change.
I have one filter I set on the one which full of red cherry shrimps at night. While the tank which where the shrimps dead don’t but I move the filter during the day, it’s been fine while my aquascape is indoor.

Also the dead shrimps have one similarity, there were red on their heads, I think it’s blood. (@lila corrected me, it’s not blood)

Edit : I just gave shading to my aquascape, but I don’t know whether the shrimps dead at night or morning, because I just put it outside on 5 pm which isn’t a bright sun at that moment only in this morning the sun is bright.

The weather is early dry season, there are only rainy and dry seasons. The outside is on the high balcony not ground.