Are they inside? it could be you have not done the ventilation right. Smoke will put the fire out so you need to make sure you give it somewhere to go, have a look on youtube for guides

Also something close above the fire will put it out sometimes, probably because e of the smoke as someone else said

Did it run out of wood? They periodically need new wood added to them.

did you add more wood?

You have to make sure the fire doesn't smother. The smoke outlet must function properly.

Did you try unplugging and for a few seconds then plugging it back in?

Seriously if you are close to the shore the water can rise up from underneath and put it out. You may never see much of the water. In which case you will need to raise the ground a bit. If you have not chimney it will go out

Does your campfire have walls, or poles surrounding it? I often place my fires outside along the edge of my structure. I like to wall them in too and make a chimney for them. If you're placing walls around a fire, you're better off placing the walls first and then placing the campfire centered so it's not touching any nearby walls/building blocks.

Even with proper ventilation, it seems the fires will choke themselves if their smoke is not able to escape because of interfering walls or wood poles.

This is how I usually build my fires into a building.

https://imgur.com/lqkSh7x

https://imgur.com/N2EruWc

https://steamcommunity.com/sharedfiles/filedetails/?id=2717025609

https://steamcommunity.com/sharedfiles/filedetails/?id=2728640407

https://steamcommunity.com/sharedfiles/filedetails/?id=2728640376

Ok, I think the culprit was the smoke.

I put my fires outside near my wall and put a roof above it. It seems the fire that have been turning off had roofs that were rather low (no snap placement).

Thank you all for the replies.