Mp3 car problem

I have recorded more than 600 songs on USB which I made in m3u format with mp3tag, but the mp3 player in the car does not extract all of them. It tells me less of what the real number was. What should I do ? I have Toyota Prius 2017

Consult the player manual?
This especially on whether the player supports playlists at all and whether there is a maximum number of tracks (like 512).
Then ask Toyota?
And after you found out the features of the player and need hints on how align tag data with the player's features, this forum will only be too glad to help.

And perhaps to clarify: m3u files are plain text files with a list of files - there is nothing to

like from a zip-archive (or similar).
So you should also check whether all files that are listed in the m3u-playlist file are actually on the thumb drive.