In addition to what the previous two users mentioned earlier about you using the Electrum wallet, you can go to the console tab on Electrum to check if those change addresses belong to you or not:
^{- I haven't used Bitcoin Core for a very long time but IIRC, there was a workaround in its coin control feature to force your main address to be the change address instead (it's not recommended)!}

• ismine("COPY YOUR ADDRESS HERE") > Click enter > If it shows True, it belongs to you.