So I watched this movie, after having watched a very similar korean drama that was also released in 2018 called "Mother" or "Call me Mother", and because of this it makes my review a bit less than others.
The main reason, is that the story line and plot are very similar to the korean drama that was released in 2018, which was also based on a japanese drama release a few years ago.
The premise is pretty much the same, where a woman finds a girl child freezing on the street with little to know clothes and obvious signs of abuse. She tries to help the traditional ways by reporting to the police, but the child always is sent home, and then more abuse happens. The woman then is worried and finds the girl and decides to "kidnap" / "save" her.
The abusive parents are also very similar, both loser dads are horrible gamers who are sore losers and click the mouse really hard. The loser dad's girlfriend is woman who looks and acts like a nice person, but doesn't really care about the daughter and hope she dies.
The difference between Miss Baek, and Mother is this:
The main character who saves the young girl is a bit different.
In Miss Baek, she's a person with a previous criminal record and served time for attempted murder, when a young rich kid tried to rape her in school. Her mother was an alcoholic and abusive, and woke up one day and decided she needed to abandon her kid.
In Mother, the main character is a University degree research of birds, and has a good job, and just got an offer to teach in iceland, so she's the total opposite of miss baek, in terms of financial standing and in the society. But she also had her biological mother leave her, and so she also has mother issues.
Overall, I would say that if you have watched Mother 2018, than Miss Baek, is a good summary theme of the Mother 2018 korean drama with minor differences because it's only about 1 hour and 45 mins long, versus a korean drama with 22 hours of story.