I tried to look up osram-dp2i-avahi but it doesn’t seem to exist in the store. Are you using a brand store? If so, please contact your brand store representative.
If not, it seems you are slotting one of the avahi-* interfaces. When using slots, you are stating that your snap will provide the service to other snaps as opposed to consuming (via plugs) a service provided by the system or another snap. Does your snap intend to provide the avahi service or simply want to use the service?