It’s definitely not an Eurowings flight, the only EW flights ex BRU at the moment are to secondary German and Austrian cities IIRC, all other EU flights are “true” SN, i.e. no miles for you but lounge access. Maybe the note in your receipt is due to the fact that SN is nowadays a subsidiary of Eurowings GmbH or just a common interface issue between the LH IT and UA, who knows.

You can also check the SN flight numbers (SN3271 and SN3732) on Flightradar24 and see that they are operated by SN aircraft.

On another note though, you can expect that at some point short-haul SN gets completely absorbed into EW, eliminating *A benefits completely ex BRU, unfortunately.