Why most converters keep your location
A typical converter decodes the HEIC and copies its EXIF block into the new JPG, because that is what photographers usually want. That means the GPS coordinates move to the JPG too. BlankAI writes the JPG from pixels only, so none of it carries over, and the report shows what was left behind.
Quality and color
HEIC is decoded once and encoded once as JPEG. Quality 92 is the default; choose Maximum for 100, or Smaller file for 82. Colors are converted to sRGB, which suits the web and most apps.
Converting on an iPhone
In Safari, tap the upload area and choose Browse to pick the original from the Files app. The Photo Library picker may convert the image to JPEG and drop the location before BlankAI sees it, depending on your Options setting. To stop saving HEIC at all, set Settings, Camera, Formats to Most Compatible.