Upwards pointing redstone does not power upwards

After 20w18a when they have made redstone a lot more consistant, RayWorks found 1 inconsistancy in his video. the redstone dust appears to be pointing upwards but does not power the piston above it. I took a screenshot from his video. Although in the screenshot the upwards pointing redstone didn't power the redstone dust above, this can be reproduced by having the bottom redstone have a signal strength of 1.