Rclone doesn't preserve some photos' date

[henry1]

I am using rclone to upload some photos from my local to google photos. It works great except I noticed that there are some photos appeared in "today" in google photos, it seems rclone doesn't preseve the correct date for those photos. Most of photos have correct timestamp.

The command I use is:
rclone copy . xxx:upload -v -M --exclude .DS_Store --ignore-existing

As I read that with "-M" switch rclone should preserve the metadata for photos.

Here is one example, the creation/modification date is 2020/1/20. However in google photos, the creation date was set to the date/time that the photo was uploaded:

What could be the reason? Did I use the correct command and parameters?

Thanks.

[kapitainsky]

As per docs:

Modification times

The date shown of media in Google Photos is the creation date as determined by the EXIF information, or the upload date if that is not known.

photos without EXIF info will show upload date.