Run this command on a file
exiftool -time:all -G -a -s file.jpg
You should see something like this
CodeSelect
C:\>exiftool -time:all -G -a -s y:\!temp\Test4.jpg
[File] FileModifyDate : 2000:01:01 02:00:00-08:00
[File] FileAccessDate : 2022:09:05 14:51:30-07:00
[File] FileCreateDate : 2000:01:01 12:00:00-08:00
[EXIF] ModifyDate : 2018:12:16 21:00:08
[EXIF] DateTimeOriginal : 2018:12:16 21:00:08
[EXIF] CreateDate : 2018:12:16 21:00:08
There may also be time stamps that are [IPTC] and/or [XMP].
The time stamps that start EXIF are the important ones. Those are actually in the file. The ones that begin [File] are the file system ones and can be a bit fragile. This is why you should check your files with exiftool before you try to add data from the json files. Google does not remove any data from the files. The only time you need to import the json data is if you made changes on the Google website.
When the data is already in the file, you can copy that data to the file system time stamps with
exiftool "-FileCreateDate<DateTimeOriginal" "-FileModifyDate<DateTimeOriginal" /path/to/files/
For video files, you would use CreateDate instead of DateTimeOriginal and you would add -api QuickTimeUTC