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Certainly! There are many varieties of Rhubarb and they come in pink, red and green colors!

https://www.gardeningknowhow.com/edible/vegetables/rhubarb/types-of-rhubarb.htm

Depending on how old your Rhubarb plants are, the advice is a bit different.
If you plants are new or only 2 or 3 years old, leave at least half of the Rhubarb on the plant to feed the plant.
If the plant is older and well established, you can remove all of the Rhubarb from the plant.
You may have more Rhubarb that grows and can be harvested into the late summer or fall.

https://www.gardeningknowhow.com/edible/vegetables/rhubarb/grow-rhubarb.htm

There are some heirloom varieties of rhubarb, such as Victoria, that have green stalks. They are perfectly fine to eat.

I'm suspicious of the watering you mention.

The leaf does not really appear as a leaf spot disease, but more clearly matches the description in the last paragraph of the article below.

I have not been able to locate an image that matches your leaf coloration.

https://www.gardeningknowhow.com/edible/vegetables/rhubarb/brown-splotches-on-rhubarb.htm

I would move the container and water with a different source of water. You may even want to flush the soil with fresh water.

This article should tell you everything you need to know about what to do with rhubarb at the end of the season:
https://www.gardeningknowhow.com/edible/vegetables/rhubarb/protecting-rhubarb-in-winter.htm

To keep the rhubarb plant productive, you will want to cut the flower stalks out of the plant.