My husband still has a good appetite and will eat whatever you put in front of him. He can eat and snack all day but continues to lose weight and has issues with bowel movements. But my husband's doctor told me was that because the brain is slowing down so are their bodily functions. Just like your mother, that constipation comes into play. As I previously suggested to you, pears/pear juice really do work if you want to do something naturally. Stool softeners do help.
Also, Miralax works well. It lubricates the stool so there isn't any cramping or excessive gas. And you stated that she is a private woman, and you giving her an enema is embarrassing. Just comfort her and continue to advise that you're do this to help her. ❤️

I’m doing the same with my mom, our situation is the same.

I think this is part of her deterioration. We are at the stage where he sometimes knows he has to go to the toilet but doesn’t know what todo so I have to show him how to sit down and urinate and have a bowel movement but he doesn’t allow enough time to finish so is up before he’s done . I have to be ready to use moist wipes to clean him then use waterproof underwear. These are a blessing. Even when he urinates in his sleep, because he’s not aware of the urge, we get through the night with only a slight dampness on the sheet under his buttocks. We are using a waterproof mat here also. This is what is now our routine. As our priority is his comfort we do what works. I can share with what details you need if you.respond. Don’t be alarmed, you can do this!

My mom doesn't have that problem but I personally ally lol use miralax everyday because of medication I'm on. Is she on any meds. I use more than they suggest or it doesn't work for.me. not sure if this helpful so if it's not I wish you the best

I don’t know what stage dementia your mom is in but it’s most likely just the progression of the disease. Just my opinion but I doubt Covid had anything to do with it. The only thing I can suggest is adult diapers. Good luck and please keep us updated. 🌹