1) Create a WEBP with a resolution other than 72 PPI by either method:
a) Menu → File → Open a 144 PPI original then → Save for web… with "Embed EXIF" on , "Reduce to 72 PPI" off.
b) Menu → General Metadata → Metadata Specifics → Change Resolution lossless…: With "Always create EXIF" to 144 PPI.
2) Result: The resolution info for the WEBP with a 144 PPI
a)
b)
c)
d) I used "Refresh thumbnails", I reset the cache via Preferences, and I quitted and restarted GraphicConverter. All did not make a difference.