Thank you for reaching out. You do have a fungus on them. It is probably septoria fungus.  Also I see some powdery mildew.  This is caused by too much humidity or possible wet leaves from watering and not getting the chance to dry out.There’s probably not much you can do about it this time of the year.

Neem oil will help it from spreading. You can also spray it with a fungicide containing copper or chlorothanil but the temps need to be cooler and should be sprayed before the fungus shows up.

Make sure the mulch is moved away from the stems of the plant. It also may be beneficial to remove all of the mulch around the plants for the winter and dispose of it.

If you water, do so early in the morning so the leaves have a chance to dry.

Be sure to remove all leaves, etc at the end of the season as the fungus will winter in them.

You may want to consider cutting back the infected plants and getting rid of them and let them restart.