There is a system that allows typos, which means that words that are kind of similar are also accepted.
For example, if you write “udnerstad” instead of “understand”, wanikani will still accept the answer. It’s kind of based on an acceptable percentage of the word being wrong. (For more info, Google Levenshtein Distance.)
However, sometimes a word that is wrong is unjustly accepted due to this.
For example an older issue was “mother” and “father”, or “winter solstice” and “summer solstice”.
For the first blocked kanji in the list, the meaning of fake (which is described with the kanji 偽) is blocked for the kanji sake (為). You can see how they are similar and easy to confuse. Someone who would fill in fake for both or sake for both would incorrectly believe that they are doing the right thing due to the typo correction. This is a nice balance of typo acceptance and the removal of incorrect answers.