Mixdown sounds brighter than the project file

Hi! I have been using Cubase Artist for a few month and i recently started to make more and more mixdowns. Unfortunately the mixdowns (without effects) are sounding brighter like it was boosted at around 6-10kHz compared to the source material. For example i made a mixdown from a solo piano recording without any processing just for sending it to a friend how it sounds without effects and unfortunately the difference was quiet obvious. I recorded at 96kHz 24 bit and exported in the same format, i am not sure that from a simple exporting the sound should change that much! I am using windows 10 and a Motu 8 Pre-es . Thank you for your help and reply in advance!

How are you listening to the mixed down file?

What type of media player, etc.?

If you import the file back into Cubase, does it sound the same as before exporting?

Thank you for your reply! Yes, i imported the mixdown back to cubase just to compare it with the original recording and yes, unfortunately it sounds brighter (a little forced) as i mentioned. (I am using a Motu 8 pre-es on windows 10).

Have you tried placing the dry recorded piano on one audio track and the imported mixdown version on another audio track, then inverting phase on one of the tracks? And there is actual output?

Not to doubt you, but expecting a certain outcome can lead you to hear it that way.