Has your LO ever tried to make a phone call from the TV remote?

Oh yes even in the moderate stage that will happen. In that stage they actually get embarrassed when you point something like that out.
Now in the major stage my mom just used the dustpan w/long handle to sweep the floor with! I just watched her for minute then went and said, "here mom this broom may do a better job at that." She just replied, "oh ok thanks baby."
She worked hard all her life raising us 5 kids so still thinks she has to be doing something to help me, but can't even fold the clothes anymore. It's soooo bad.......
But I am just trying to keep the promise I made to her when she was first diagnosed.
God bless you and yours for trying to take care of your LO.
To me it is the MOST admirable thing one can do!

My mom did that all the time. Actually I've done it once or twice too. The phone and remote have to be in very different locations. Now she can't use a remote or a phone, so at least your mom can dial and press buttons. Hiding her confusion is sad, but that just means she's aware of her failing memory.

I've seen elderly people do this on several occasions. Different people.

Maybe your mom isn't trying to hide it as much as she's trying to deny it.

I brought a new phone in for my aunt (92). She was watching TV and had her remote in her lap.
I showed her the handset on the new phone and told her to compare it to the old phone which was by her chair.
She held both in her hands and said “the numbers are much larger on the new one. I like that. “.
This was true. I was happy she noticed that right away (although she doesn’t make calls any longer and doesn’t use the numbers. . .)
in just a nano second, she had all three of the devices in her hands wanting to know what to do with all the phones. She totally saw the remote as a phone. When I pointed out the one that was a remote she said “yes”. It was like she saw it as both a phone and a remote at the same time.
And the remote doesn’t have visible numbers at all. It just has an arrow up and down for volume and channels although she can tell you her local channels easily. It’s so fascinating how the mind works. She knows and at the same time, she doesn’t know and of course, as time goes by, not knowing will take over.

Yes, this is normal. They are similar in looks. My Mom forgot how to use both.