Responses
While I haven’t read this yet, is it possible he’s seeing the old FL in her and he senses that her soul is the same?
(I know I have no right to comment yet, but I feel like my question is probably closer to the truth. That kind of trope is common because it’s popular. If I’m wrong, I’m wrong. ╮( ̄▽ ̄)╭)

I hate it that the ML falls in love with the FL in this new body.
Like in his eyes hes falling in love with another woman and forgets about the old FL. Even if its the same Person, its basically still another woman! I hate this Kind of plot