I usually think of mold, fungus and mushrooms needing very organic soil. maybe your soil has too much compost, or too much fish emulsion.
Usually a dry surface discourages fungi. If you can scrape off the top layer and replace it with something that will drain instantly and dry quickly, that might keep the fungi below soil level and out of your lungs. Like coarse gravel.
I like bark chunks (pine, fir or balsam might be best) as a top-dressing. Since you want them to dry out quickly, those chunks can be 1/4" to 1/2" in size, and 2-4 layers deep. My Lowes sells clean, dry "Fine Bark Nuggets" in 2-cubic-foot bags for $4.25.
If you can find pine bark nuggets, those are also a cheap way to lighten up a potting mix and make it drain faster. Like very coarse Perlite but much cheaper.
If you can't find bark nuggets, you might try a bag of medium bark mulch ... but you will have to screen out the big chunks, and even more important, screen out the powder, fines and small nuggets. Bark fibers and fines will hold almost as much water as peat. Often "mulch" is loaded with dirt, wood chips, pebbles and moisture. Yuck.
Any bark that is too big for potting mix can be chopped or ground up and then re-screened. 1/4" and 1/8" hardware cloth are useful for screening.
Once you find a source of "grit-sized" bark, like the size of BBs or somewhat larger, you can make any commercial potting mix much cheaper by adding lots of bark. For VERY well-draining mix, you can use mostly bark grit plus 10-25% commercial potting mix.
Make it drain faster by screening out ALL the bark fines and dust that you can.
Make it hold more water by allowing it to keep some of the bark that is finer than BBs.
