@Another new name Sue, at this time of year, I am seeing squirrels searching for nuts they have buried over the fall so that is where I see breaks in my mulch.
Mulch is great for many reasons I have previously mentioned — keeps soil temps even, reduces water requirements for plants & acts as a weed block for many weed seeds. Yes, you will get some break through of certain weeds in mulch such as clover, certain thistles or maybe crabgrass or some grasses spreading through their underground runners.
In my experience, mulch reduces my weeding time to very little. If you see crabgrass, try and remove it completely before it sets seed. Thistles like dandelions have taproots so that forked dandelion tool works really well at removing thistles too. In certain areas of my garden, like my rose garden I apply cedar mulch, then sprinkle Preen without fertilizer in the container over it. At least the Preen acts as a protective weed barrier for several months provided you do not break through the soil & dig it.
In places where you see bare soil, you may see tiny holes. Could be evidence of ground dwelling bees or with larger holes, cicada wasps nests for their one egg with a food source (a stunned, stung cicada).
Ants are always foraging so there will be ant hills among mulch at times. Either live with it or pour boiling water over the area. They do serve a purpose — aerate the soil, help distribute microbes through your soil.
☼The best place to seek God is in a garden. You can dig for him there. GBShaw☼