Bimyou (微妙) is a kind of negative space, a vehicle for doubt or uncertainty or anything counter to the expected flow of an interaction.
“If I asked you how a restaurant was and you replied with ‘bimyou,’ I’m not going there. If I gave you a gift and you called it ‘bimyou,’ I’d think: ‘Great, she hates this gift.’”
In speech, it can be used to describe anything from a sensitive issue (微妙な違い) to a tricky political relationship (微妙な関係). More recently, young people began using it as a way to express negativity or apathy, a kind of verbal shrug.
The Good, the Bad, and the Bimyou by the Foreign Policy https://foreignpolicy.com/2022/01/07/japan-bimyou-subtle-apathy/