You have a data file.
$ file data
data: data$ head -n 1 data
PXMDMETA�bplist00���X$versionX$objectsY$archiverT$top���/0123456789:;<=>?@ABCDEHOPVZ^adefguvwxyz�������U$null�Google PXM file.
It's a binary file for Pixelmator, a graphic editor developed for macOS.
Check if there is a trial. There is, download it, add extension to the file and open it.
There is 3 layers:
- cat
- black
- flag
Uncheck all layer, except the flag.
You see a text image on a white background: flag{y0u_F0und_m3_!!!}.