Q.Why Is One Leaf On My Calathea So Big And Should I Prune It?
The tall leaf shown suddenly shot up one day and use to stand tall but more recently is has gone quite limp. I repotted the plant today thinking roots might be too small for the height. However I think it just looks odd. Should I cut the large steam at the soil level?

Certified GKH Gardening Expert
This happens with a healthy plant, for the most part. The large leaf is a good sign. The length of the stem indicates that it may want just a little bit more light, though. It doesn't look like it is lacking in light,badly, but they stretch when they want just a little more. Do not cut this off. It will be more of a risk to the plant to cut it, than leaving it attached.
Overall, this doesn't look unhealthy. Care must be taken when repotting, however. They are very picky about the type of soil used.
This article will help you with the care of Calathea:
https://www.gardeningknowhow.com/houseplants/calathea-plants/peacock-plant-care.htm