Playback of exported mp3 or wav file not 'steady'. Although not a problem in musescore itself.

I hope I'm in the right place here on the forum.
I'm pretty new to this so got to find my way here.

I wrote a piece in Musescore 4 which sounds good when playing back in the program.
But...I tried exporting it in both a mp3 as wav file and they're both a bit (sometimes a lot if you'd ask me) 'off'.
Meaning: the notes are not 'steady in the measure'.

I tried several things like restarting the program and make a new export..but that all doesn't work.
Is there anyone who's had the same issue?

Thanks for your reply.