A Love So Romantic (2020)

Cute outgoing FL that lies so well and loves $$
Cold / Warm hearted ML
There's a murder somewhere

All the Cliches are in place:
-child hood connection
-so so 2nd leads that's been "friend" zoned
-Evil woman that wants to kill the FL
-FL needs to randomly fall so ML can catch her and do a staring contest

A story that follows the quirky female investigator Tian Sanqi as she searches for her long lost 'brother' and cracks many cases along the way.

Growing up, Tian Sanqi had a strange liking for performing autopsies. She had an older 'brother' who would always be by her side and they spent many good years together. One day, he mysteriously disappears. Sanqi as a child promises to find her true love and vows never to marry unless it's him.

In her search, she comes across many potential candidates and forms new friendships. The gang accidentally becomes involved in several cases in the area one of which seems closely related to the disappearance of her 'brother' all those years ago. A shocking conspiracy that is 10 years in the making comes to light.

Similar premises for the plot: FL hired by ML to play his long lost younger sister...
Of course there will be complications.

Very similar fluffy romance dramas with a FL sleuth that helps to solve crimes. Very similar tropes and storylines.

Both are historical dramas with a heavy love triangle in which the FL spends more time with the SML than the ML. Both involve one of the leads developing amnesia for a while, one of the leads thinking the other died, and end with the FL returning to the ML and the two and their child living happily ever after. Both stand a good chance of giving you SLS.

In both dramas FL will get into ML's house by fake identity. ML is cold and aloof but will slowly warm towards FL who is bright and will often get into embarrassing situations.

Both are historical romance dramas in which the FL ends up entering the ML's family under a false identity, but the two fall in love.

One is modern and the other historical, but both have the same basic premise of the ML convincing the FL to pretend to be his long lost sister to make a grandparent happy. Along the way, the two fall in love.