Some may find it unappealing when the ML already has a son, however I think, the son's identity here contributed a lot to the story's enjoyment factor. He liven up the atmosphere tenfolds.

MC approach ML after his rebirth not because he has feelings for him but because of pure gratitude. The same for ML, at first his interest was just piqued, but it's nothing more than that. Although I'm not sure why he was helping MC so much for years in his past life even when they don't have relationship. The MC thinks the ML is just playing with him, but logically speaking, who would spend that much attention, time and effort to someone out of mere entertainment? The author never made it clear though so we can just assume.

Except for Kang Jian (the s*um ex). I think the author just decided to push all the hate to Kang Jian's character, I mean all throughout the story he was a complete scum, no remorse whatsover. Irredeemable. Greedy to the max. I mean, I get it human greed are insatiable but at the end of the day we are still humans. No matter how bad we can be, there's always a reason/motivation behind every actions. No one's completely black and white. Kang Jian isn't. He's the antagonist so all his actions are just pure antagonism. It became unrealistic to the point that I don't care whether he got his punishment or not in the end because it doesn't matter anymore, because as I've said, he's thoroughly blackened. What would you look forward to to a person who is expected to not have any remorse until the end? Nothing. His character became bland in the later chapters. Also whether he has family or not, it remained a mystery. The author didn't bother providing background for him.

Who is the mother of ML's son? Why did she escape? No reason provided. Why MC knows what happened after his death
in his past life? I'll try to answer this. Maybe after he died his soul lingered for a while before he went into the cycle of rebirth so he still managed to witness what happened after. Author didn't make it clear though.

1st: Honestly, this started off as dramatic and kinda light hearted. And then suddenly pop! There's an evil nanny who only showed up once and has the intention of making the ML's son permanently disabled. The nanny was immediately caught and forced to jump to death by the ML. Thrilling right? It left a deep impression on me. But rest assured, there'll no more anything darker than this, which is kinda disappointing, because this scene kinda set the standards.

2nd: A friend of ML pulls a trick of triggering MC's heart attack by abusing him on set. How serious this can be if it succeeds? MC would be dead in an instant, again. That's pretty dark. I think ML's reaction regarding this fact was a bit lackluster, or too calm. It turns out great though. He handled it pretty well.

Such as when ML discovered MC has heart disease, and when ML got into a car accident. However just take it as me nitpicking. I think the author still delivered the scenes well in that approach.