Who said that downgrading use less data while syncing?

Honestly, if you are going to use the lower version, you will experience the bugs that exist on that version. That is why they keep updating or releasing a new one is to fix those issues and improve performance.

How exactly did you set up Bitcoin Core to prune? You might have entered a large size. If you don't want to consume more mobile data, then try lowering them to "550MiB" which is a minimum, or just set it to "2000MiB".

Also, tell us the exact specs of your laptop so that we know what the cause of your slow syncing process is.

If you intend to use it for daily transactions, I recommend switching to a lite version such as Electrum if you do not want to continue experiencing syncing issues (in the future if this one is fixed).