Not sure that I like my own mother

You don't have to have Alzheimer's to be annoyed with people having children they can't afford! It's just common sense.

Has she recently retired?

My parents had too much free time on their hands when not working, and started developing really weird opinions and theories about the world.

And realising you don't like your parents is quite liberating in my experience. You can love people but not like them.

I don't think 65 is that old - she would have been a young adult in the 80s and benefitted from changes in society that took place in the 60s and 70s so if these opinions are new I agree it's quite disturbing. It may be that she has thought them for a long time and now feels able to articulate them. I know lots of 60s 70s and 80 year olds who would be appalled by her views. So I also agree with other posters that is this seems very new to keep an eye on other aspects of her wellbeing

in the end they are all just opinions.

Well not really, because they affect the way people vote, which then has an effect on real people’s lives. You could say that being anti-abortion was ‘just an opinion’ in the States, but given that pre-teen girls who have been raped are now being refused abortions in their home states, and won’t get one at all unless they’ve got the resources and the support to go out of state, which very much isn’t a given especially at that age, I’d say that they’re a bit more than ‘just opinions’.

Has she got more time on her hands so that she's thinking about these things? She might be spending time ruminating.

She might simply disagree with you - I'm sure you feel that your opinions are the 'correct' ones but in the end they are all just opinions.

In terms of not allowing any discussion - was this always the case or is it something new.

Sometimes it's a reflection on age, how the world has changed since you were young and maybe missing that youth/world. Added to a rose tinted view of the past.

I think the phrase 'we'll have to agree to disagree on that' will help.

Is she spending a lot of time online? I think we spend so much time worrying about teenagers using the internet, but actually older people are very ill-equipped to deal with it too. My FIL is addicted to his phone/laptop and gets all his news from rightwing sources that used to be fairly moderate but now serve up a steady diet of fear and outrage for clicks. Combine that online content with being retired, and so having fewer contacts with the real world to remind you it's not all bad, and you have a recipe for angry old folk.

@Harara I don't agree with her, but I've a relative a bit like this too and it's just pointless trying to change his mind, and I can't be bothered arguing with him about it.

She has probably always thought this but maybe you just didn't notice, now she might have a bit more time in her hands so she just voices it. She doesn't sound particularly pleasant.

Assuming the OP’s a woman, then being anti-feminist is personal to her. And if she has any LGB or not-white/not-Christian friends at all then so are some of the other views. I assume the people defending OP’s mum are those who sorta agree with her, tbh.

I'm 63 and yes, I think I am now more opinionated (but not in the way you describe!). I now have the confidence to let people know what I think. I dont, most of the time, because I don't want to cause ructions and some of my opinions are certainly different to those of my daughter. However she does not have any issue with letting me know her opjnions, even when she knows they are different from mine.

Everyone is entitled to their own beliefs, opinions, whatever. What they are not entitled to do, whether they are 30 or 60, is to push those onto other people.

Quite frankly there are times when I don't like my daughter very much - but I love her to bits.

This. You say you understand she's entitled to her own opinion so keep reminding yourself of that!

She doesn't have to agree with you about anything and vice versa.

Perhaps it is age related, you're not her age so you can't relate, maybe your views will change 30 years from now, who knows, but she's just as entitled to think whatever she wants about anything as you are....your views aren't more valid just because, in your opinion, they're the 'right' ones.

I’ve heard that we tend to get more conservative as we age. My Mum became a bit like you describe, she was particularly annoyed by people having children they couldn’t afford and other similar things. Eventually she developed Alzheimer’s so I’m not sure if these issues are related

What was she like when you were growing up ? Was she always a bit like that ?

Try and not let it bother you, it isn't like it's personal to you ?

I can relate to this. My mother, as she is getting older has become more and more bitter and entitled. She believes her opinions to be factual. She thinks she’s right about everything, has an extremely suspicious mind and can gossip about anyone and anything. She comes across extremely bitter and jealous. She likes to override everything I say in front of my children and if I even so much as roll my eyes at her she will have a full on toxic argument with me even if I try to abstain she will provoke a reaction at some point.
I used to really get along with my mum and look up to her and it feels really crappy that I have this really negative perception of her right now.
so no advice here, just that I can relate x

Are there any potential medical factors, e.g. might she have high blood pressure if she seems to developed a very short fuse? I know that doesn’t make her political opinions better, but if there’s a personality change I might wonder if there are factors like that at play. It does seem like it can change someone’s personality unfortunately.