When I look up some Kanji on websites like jisho or japandict, it sometimes says “usually written in kana” or “also written as” an then showing the kana reading. I do come across native Japanese words written in kana sometimes while having Japanese subtitles on or reading manga, but I thought it might be due being orientated towards a younger audience.
For example, for 葱 they say “usually written in kana”, and WK teaches on lv2 玉ねぎ and not 玉葱, so I assumed that the Kanji version was simply outdated or that it was easier to use the kana version since people just knew what was meant by that. Same for some animal Kanji like 鴨. But while I frequently see ウソ written like that, 嘘 is still marked as popular word, so I am just wondering about the reason. I did a quick search on the net, but couldn’t really find anything useful.
My question now is would you advise learning Kanji like 葱 or 鴨? Are the Kanji versions useful to know for test like the JLPT?
Thank you in advance.