You are not alone.
I am the product of an unplanned pregnancy which I feel sure - and it's even been alluded to - my mother thinks trapped her with my father (abusive alcoholic)
When I was younger I couldn't put my finger on it but I felt less "liked" by my mother than my siblings.
Nothing is EVER her fault, and she'll never accept she had any choice or agency in her decisions.
She's also admitted to being jealous of mine and my fathers relationship when I was younger, I was "daddy's little girl" he was obsessed with me and possessive but instead of seeing that as the creepy, predatory thing it was (not clear to me until it became undeniable) she resented me for it and I think viewed me as a "romantic rival" - how fucked up is that?! When I disclosed she didn't believe me, still doesn't. Others do including her own siblings who despair at her attitude to my father (won't hear a word against him).
She favoured my sister in particular, still does, and my brother and that's been visited on the next generation with my dd bottom of the pile!
She'll SAY she loves me, but she doesn't show it.
I'm nc with my sister (yes in part due to our relationship is messed up because of the sg/gc nonsense, but also because my sister is toxic and abusive and turning into my bloody father), vlc with mum and dad and sort of medium contact with bro, who distances himself from us all really - I don't blame him!
The relief I felt at uni when it turned out 2 fellow students also didn't have good mothers was immense.
Some people should never have been mothers, or at least not had children with the people they did.
"they too must have had poor relationships with their mothers." Not always - that's what's so odd with my mum - she came from a normal happy family. Her own siblings don't understand the hold my father seems to have on her - and did from the beginning.
The one time my experience has been somewhat useful is as a nurse in elderly care. If you think not liking your mother is taboo, good luck getting honesty on abuse of staff by elderly patients! Some of the other staff members would voice sympathy for the "poor little old lady/man who's family never/hardly ever visits them" I'd point out they don't know the history, that "poor little old man" wasn't always so, they were once a young, physically fit man who could well have had their faults which is why their family is distant. It was useful because these patients/clients required a slightly different approach sometimes. My stance on this was ignored in one place I worked and a patient broke a staff members arm. The patient concerned had regularly beaten his wife and child as a younger man, he played the "frail old man" with new staff members but then if they acted or said anything which displeased him he'd lash out - and he was actually still quite strong and a walking stick can cause serious damage! Her crime? She'd told him off for a comment he made about her arse! He didn't even do it immediately he waited several days until she was in a vulnerable situation with him and there wasn't anyone else around.