Personally, I've not seen the watercolor effects that you are saying so it may have already been fixed in the later firmware released. Now already hv Dec patch with some battery optimization. Or probably haven't really shoot in really very low light but you can read from herePersonally i feel m10p camera is worse than oneplus 5t. Don't have much clarity in the photos and lowlight watercolour effect is obvious
https://fstoppers.com/originals/look-huawei-mate-10s-ai-assisted-low-light-photography-201821

I used a debit card if i remember correctly so if i refund will it be like the credit-card kind of refund (ie, 3 weeks