The antenna is located on passenger side on the front cap. There are 2 (on my 2018 DX3) one is Sirius/XM other is GPS. Both are molded antennas. (no external connections) They look like a black squarish bump on the fiberglass.
I would suggest you check that the antenna connection at the Sirius receiver module in your dash has not worked loose. Remove and reseat. See if the check antenna goes away.
You could also have a corrupted cable which would require a replacement which are readily available.