To reproduce the bug, place two dissimiliar stairs to form a corner.
Waterlog the corner.
What happens here is that water will flow from what is supposedly the 'wall-side' of the cornered stairs, but only if the two stairs are of different types.
In my build I used copper, which oxidizes, hence why the problem did not initially occur.
Thank you in advance.
Thank you for your report!
We're actually already tracking this issue at MCPE-104070, so we will resolve and link this ticket as a duplicate.
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