I'm confused, someone help, what're these flashbacks??

Yup. ML's pov

So he also got reincarnated???

That's also what confuse me, I don't think that's the case, he doesn't seem like someone who have his previous memory, he act different in this one, but I think it's mainly because of the FL action.

It’s most likely that we are seeing what has happened to him after the MC died. He’s explaining why he did what he did and is wondering why her “spirit”( the image of the mc doing things around the estate) was suffering alone and why didn’t she assert herself

What I got from spoiler
.
.
.
.
.
..
.
.
.
He the one who reverse time and also he remember the past life. When the scene he was in dirty cloth and look old is because his son became crazy as he learned that the person who raise him is the one who kill him biological mother, so the son shut his father(old ML) in the same room his mother died.

So as also from spoiler, he reverse back time to avoid the same mistake like give in to his father in law threat, take his son from his mother(this is not his fault tho, fl was mentally unstable and he was going to bring mother and son together again but his fil being villain he is, drag ml in war for years so he manage to hold reunion between mother and son as in first chapter we read but from ml pov). Hence, that's why he know everthing about to happen in current life.