Very worrying, especially if she's not actually got dementia yet, as they're the signs she's heading that way and will probably accelerate if she does start down the dementia road.
Sounds like she needs some "hard love" to take more responsibility for herself and stop relying on others, as it will just get worse. If someone else is doing more and more, there's a tendency to be lazy and not even try to do it themselves or keep up with things that change.
If she's not got dementia, I think you need to start pulling back and forcing her to do more herself and taking more responsibility for herself. However hard that may be.
From my (very limited) experience of parents, in laws, etc., it seems to be a slippery slope that turns into dementia after a few years. My mother started going down the road, but I applied the "tough love" and made her continue to do things, learn new things, never took over if she was struggling, never offered lifts for short distances she could walk, etc., so we kind of reversed the trend. Obviously can't prove it, but she never got dementia despite living into her mid 80s - brain still sharp the day she died, and happily using online banking, smart phone etc.
My MIL is the opposite. Obviously I can't control her as I have to leave it up to OH. She was going down the "helpless" route in her 60s and it just got worse and worse, the less she did, the less she could do, a real downward spiral, but brain was fine, it was just sheer laziness especially as she knew someone else would do things for her, run around after her, etc - being in your 60s is way to early for that kind of dependence and incapability especially as she had no illness or health problems. After around 10 years of regression, she started down the dementia route - again, can't prove it, but I think it was lack of using her brain, lack of exercise, etc that actually brought on the dementia in the end. Now she's barely capable of anything.