My mom treats my boyfriend like a son even though he’s not saint

Hi,I'm not a bride but I became a member of this site because I desperately need some opinions. This post is about my mom and how she acts towards her future son in law (my boyfriend). Sorry if this is long.
Let me begin by saying that I was married in the past but got divorced. I have noticed a pattern with my mom that I’m not sure if it’s normal. She makes my boyfriends feel welcomed in our family right from the beginning by being extra nice to them instead of taking her time to get to know them well. They don’t have to try hard to gain her trust.
My mom was close to my ex husband and then I started venting to her about my marriage problems because my ex became frugal and controlling with money. I had to ask him permission to buy anything even though I worked and helped with the rent and bills. He was so cheap that he did not turn the A/C during summer when it was super hot because he didn’t want the bill to be too expensive. Thank God I did not had children with him!My mom listened to me when I told her I was not happy and told me I could do so much better but still treated my ex super nice, as if whatever I told her was not a big deal.
Now I’ve been with a new guy for a while after my divorce and my mom is acting the same way again. I know I’m an adult and I don’t need my mommy defending me, but I feel like I can’t trust her as she seems to ignore my problems/concerns. She thinks my BF can do no wrong. I know it’s not healthy to tell my mom my relationship problems but I feel like I always end up with the wrong men. My mom contradicts herself. I told her my BF has taken advantage of me in some ways and that he constantly gets mad over petty things and she even said: “yeah, he sounds abusive”. Then another day she tells me that she really likes him and he’s a great guy. One time she complimented him as soon as she saw him telling him he’s in great shape when I’ve already told her previously he was a jerk sometimes. Why is she more concerned about his physical appearance instead of the person he really is and how he treats people?Also, my BF doesn’t want to get vaccinated from Covid. My mom says everyone who is not vaccinated is selfish and ignorant and she doesn’t want to be near them. When I told her my BF doesn’t care to get vaccinated she DEFENDED him saying: “oh but he doesn’t have to worry about it”. So everyone else is bad but my BF is a saint.
I have so many problems and feel uncomfortable venting with my mom. Even though I’ve opened up and told her he’s not 100% perfect, she still treats him like a son pretty much ignoring everything I say. I’m not saying that she has to be mean and treat him bad but she shouldn’t go out of her way to be nice. She always asks about him, asks me if he ate and wants me to take him food whenever I go to her house without him. It makes me feel like she’s a hypocrite when she acts like she supports me. Recently she told me we should plan something out for his birthday but little does she know that he didn’t took me out on my birthday or bought me anything.Is it unusual for a mother to go out of her way to be nice to her son in law? I'm going through a lot right now and I'm not sure if I should continue to vent with my mom because she might still think my boyfriend is fabulous after a while. Am I overreacting?