You have to dump and rinse the dirty tank shortly after the task it’s completed. If you let dirty water sit anywhere you will have bacterial growth and it is going to become stagnant and stink.

You need to increase the frequency of mopping. I run mine every night and my water is almost clear. Also use a kitchen sprayer to rinse out the tank when emptying and the smell will decrease.

The bottom of your shoes aren’t perfectly clean…. Even your socks and bare feet, your dogs foot pads aren’t perfectly clean.
Everything you have has some form of bacteria and bacteria growth causes unpleasant smells

By the way just a heads up I know you say you use the Dreame Solution, But I had to do extensive research to find out that these robot vacuums do not mix the solution from the solution tank with water from the clean water tank, when moping your house it only uses the solutions while cleaning the mop pad. You have to actually add your own solution to the clean water tank. I found out fabuloso antibacterial works really well. You can order it from Walmart online, it's not the normal off the shelves Fabuloso.

I have seen a prominent online reviewer recommend putting a denture cleaning tablet into your dirty water container

I have 3 cats and have not experienced any foul smells.

I clean the dirty water tank after each use. If you add cleaning salution to the clean water take it will help