Spider web pattern tag is a mix of spider web print and clothing that have spider web cutout or a spider web like mesh. Spider web design's only post is of the latter kind but the tag wiki seems to imply that it can also include spider web print.
I think we do need a tag dedicated for any kind of spider web designs that's not just spider web print like post #6633742, post #8362221 and post #8327791. The question is how should we name it? Either use one of the two existing tags, alias the other or have a new tag name?