FL is a ghost, ML is trying to help her find out who she is and why she (supposedly) died. There are strong hints of police cases underlying the main plot. While doing the sleuthing necessary to solve the FL's case, other ghosts are met and freed to another plane of existence.

This setup is very similar to the Thai remake of BIOG too, Let's Fight, Ghost (not going to make a double rec).

There's a similar feeling that the story takes place somewhere outside the civilised world, where everything is allowed and still there are some unwritten rules that even the madmen and wild people seem to recognize and respect, but life is pretty cheap and usually those with power will rule, no matter their morals and ethics.

Both dramas have a distinct atmosphere of impending, relentless doom, despite the actual endings for the main characters.

Obsessive ML characters, a common theme of wanting justice (in different ways), both are period/costume mystery/judicial dramas, not a lot of predictible romance (of any type), good side-kicks to the main characters.

Also, great casts in both dramas, and very good production values.

Both detectives leading the investigations are independently rich (bringing interesting workplace dynamics), Elijah is in both of them (I thought it was just someone looking a lot like her, LOL, initially, nope, same actress), both MLs (of the two dramas) have colourful past experiences and things to clear up. Also, both MLs are definitely smart and tend to notice small details (which is always a plus.)

TGD had a pair of detectives, it looks like Bait/Decoy won't.

Depending on how Bait/Decoy develops, it might turn more noir than TGD ended up.

There are some similarities (so far) in the topics both dramas cover, like the internet dangers and security measures one person can take to make themselves more safe. There's even a pretty similar format, as in each episode includes an extra (security tips for AYS and the Monster Notes for TSOTM). There is a strong current of bromance (of the good-friends only kind) in both dramas.

Both give basically the same vibe (again, so far).

Older woman/younger man romance, the woman is a lawyer in both dramas (different type of lawyer, but nonetheless, lawyers,) Very pretty MCs, (IMHO).

A bit different background stories, but both end up as romances. SAHPH is more direct about it, IHYV takes a while to get going.

ML is crazy in both cases (or as irresponsible as they can come, in a police-type of drama). A lot of coincidental almost impossible things happen in order for the cases to be solved, but they do happen, and cases do get solved. TFR is more episodic than BAC, but there's a similar vibe to both of them.

Both dramas deal with first responders or rescuers. There's a mystery in each, and all the people in the main cast have interesting back stories.

Both dramas also involve episodic cases and an overreaching arc, and the MCs bond over their problems and how they deal with them.

Everyday's policemen work, catching the bad guys, interesting dynamics (good friends in TGD1&2, estranged father-and-son in BB), not a lot of interfering romance (if any).

Police teamwork to catch criminals (including serial killers), good bromance, interesting characters.

Based on only the first episode of Alchemy of Souls - there you have it: the horror background/aspects, the immortal souls (or possibility for immortality), the secrecy aspect, immense powers, etc.

Other than that, the plots themselves probably won't have much in common.

Two people looking - one for revenge, the other for justice.

Bromance created in times of need. Good path toward resolution.

Rookie vs. experienced person dynamics, plenty of action, very interesting - and independent - women. (IMHO both dramas pass the Bechdel test with flying colours.)