Wondering if anyone might know what the light brown spots are on this young bougainvillea's leaves? I bought it from a reputable plant centre 2 wks ago, but along with another one, it's not holding it's own much - I'd potted up the other but it's not doing very well since so figured I'd maybe let this one sit awhile longer as they don't seem to have much in the way of roots yet.

I live in the UK (west).