Regarding 龹 in kanji

That’s true. There are cases where small differences can make a totally different character, and other cases where a big difference is no issue at all.

Slightly different topic, but my general recommendation, if you are concerned about writing correctly, is to check for fonts that look more like handwriting as opposed to printed text. It’s not wrong to write something that looks like printed text, but it will stand out a bit to natives.

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