That's not what happens when you process images that have originated in Lightroom Classic on the main computer. Lightroom on the iPad sends the changed parameters in the form of data that Lighroom Classic incorporates into the catalog as changes for a particular image.
I sounds more like you had a really slow connection or didn't have the apps open long enough for the sync to take place.
PS. For photos that are created on a device (iPhone or iPad) using Lightroom (Cloud Based) version, those images are up loaded in full resolution to the Adobe cloud and you can setup a folder on your main computer where you want those images from the device saved on the Lightroom Classic computer.
Ken Seals - Nikon Z9, D850, 14mm-800mm. Computer Win 10 Pro, I7-8700K, 64GB, RTX3070TI. Travel machine: 2021 MacBook Pro M1 MAX 64GB. All Adobe apps