Hi, this is Steve and thank you for contacting Ask An Expert. We always have to ask and have you determine if there have been any type of chemical sprayed around the area that may have caused this pattern. Otherwise, we would assume this is a fungal infection. Normally, we would also see the damage on the leaves as well. In the picture you sent, I don’t see that any portion of the bed  except the blue pansy flower is affected. So, from the pictures, I’d admit it’s a bit odd. In my research, most every disease associated with pansies is treated with a fungicide. I am attaching a link that lists several options on fungicides. Be sure to read and follow all label directions if you choose to use a fungicide. Best of luck .

https://hgic.clemson.edu/factsheet/pansy-diseases-insect-pests/