Losing trust in MIL capabilities

[MILquandary]

Name changed for obvious reasons.

I will start by saying my PILs have been great since our first was born 7 years ago. We live some way away and they are always happy to come over to help with childcare etc.
They are getting older though, and just recently I have noticed more and more behaviours from MIL that are concerning me.

She is very forgetful and I often have to tell her things a few times. She loses things constantly. The last time she looked after my youngest DC whilst I was out with the eldest for a couple of hours, she did something which defied common sense and instead of phoning me to ask for help...she took another route and nearly burnt down the kitchen. She then tried to hide the evidence until I asked what the smell was. I wasn’t happy with this as it makes me wonder what else could be happening that she doesn’t tell me about?
There have been other odd things from her in the past. Won’t go through them all but she once almost used non-bio washing powder to make a feed instead of formula (I had brought it to their house with me in a plastic container).

AIBU to worry about leaving dc alone with her now? Or am I overreacting?
If not, how do I approach this? I am worried about discussing it with DH as he has historically always sided with his parents (that’s another thread). He brushes these behaviours off and it will almost certainly cause a row.
But it’s making me really uneasy. My anxiety is through the roof after having them over again this weekend.

He stayed home. They sometimes visit separately

I feel for you OP. And for your MIL, who may have an issue with cognitive impairment. And for your DP who may struggle to come to terms with it. I have been through the same (albeit with my DP on the same page). It’s possibly a painful but necessary discussion to have with your partner. The safety of your child has to come first. We just agreed to make sure our kids weren’t put into a situation where any harm could be done.

Thanks for your thoughtful message @CobbldyCook I will speak to him tonight.

It might be worth writing down all of your concerns about DMIL before you talk to DH, just as a reminder to you.

My DMIL had Vascular Dementia and it does sound as though your DMIL may have some sort of Dementia starting too but other things that can cause confusion, like a UTI need ruling out too.

And do come on over to the Elderly Parents Section, it can be wonderfully supportive and a great source of information