If it's not from being in soil that's too moist, it could be from handling as it grew before you got it. This damage can become more pronounced as it acclimates to its new environment. The spots in the mid leaf area near the bottom right look like they are a result of bruising as the leaf was unfurling.

In the photo below from today you can see some leftover creases (from when the leaves were unfurling) that are almost perpendicular to the leaf veins. The small banana tree (bottom left) and edible Yautia/Eddoes have brown spots on the top sides of some of their leaves - but because of the wind you see mainly the bottom sides of the leaves:

This grouping is not wind-protected and has some damage on all of the leaves.

Thanks a lot Jay, I’ll ease off with any watering just in case but you’ve definitely reassured me. Your help is much appreciated!