The sample you provided, red, is probably of 中学生 (middle schooler) being censored out. But once again, I don't know that I've ever seen both characters omitted before. It makes it very difficult to read while doing nothing to further censor the person's age. My guess would be that some studios and/or editing staffs feel more comfortable with the double edit precisely because it makes it so, so darn difficult to discern what was originally said. It's sort of like saying, "If writing 〇学生 is one way of covering our tracks, then writing 〇〇生 is an even better way of covering our tracks!" Why not just say 〇〇〇 while you're at it, then, Mr. Editor? lol