FYI: just the other day I lost some hair when trying to upload about 1000 .jpg images to Google Photos from macOS 13.4 Desktop. The upload always stalled between 1-17 images no matter what. (I trashed the few images that succeeded to transfer before the next try).
At first I suspected that Google Photos throttled the connection because before that I had uploaded 37 .mp4 movies (2 GB in total). But the upload did not progress for a few hours. So I waited two days, and tried again but the problem persisted.
Then I tried to upload only 20 .jpg at a time, but that also stalled around 11 images.
Then I suspected that Google Photos balked at some metadata (although the essentially same images were successfully uploaded a few years ago -- now I had slightly edited the metadata in some with GraphicConverter and was trying to upload all of them en masse again). So I edited off all unnecessary metadata with exiftool and left only ExifIFD:DateTimeOriginal, GPS, IPTC/XMP Descriptions and Keywords to 20 test .jpg images. But they also stalled at around 10-17 images.
But then I tried to upload with Chrome instead Safari and, viola!, ALL over 1000 .jpg uploaded in a breeze.
p.s. I recently switched my 2nd browser from Chrome to Firefox because Chrome and its related update processes might intervene with Final Cut Pro. So to use Chrome, I now booted to an external volume where I test and use suspicious software before letting them go to the internal work drive.
