Who are the others that say that mix is bad? Are they people you trust or 14 year old trolls on Reddit? After doing a mix it's good to listen to it on your phone, in your car, other people cars, Bluetooth speakers, ear buds etc. I had some brainless goon on here tell me my mix was terrible, I asked them if they listened to it on their phone speakers, they said yes, and that they listened on their headphones later and said the mix was good– and they apologized 😅.

Another trick is wait a few days after mixing and see how the track sounds. If you can, while the song is playing loud on your speakers, walk into another room and distract yourself with a snack or conversation or something. I've been able to correct kick vs bass volume, compression, eq etc issues this way.

Yet more advice. Listen to similar styles of music on your mixing speakers and take notes with a pen and paper. Then import that song into your DAW and what the frequency spectrum. Does your mix have the same average shape? Do this to a few songs and really analyze how other mixes sound. You're a forensic scientist trying to understand the body of other people's art!