Syncing from iCloud barely progressing

I recently bought ip15PM 1TB, 2T iCloud and having this syncing problem since the very start, dragging to forever indexing photos, battery drain, and warmer phone.

My software is updated, but same problem still exist.

I’ve asked the customer care and even talked to the senior advisor, but the problem still there.

Last week I tried sync overnight on charger but i got only 4/6 photos synced.

And after series of slow syncing, now it only says syncing… without knowing how much more I should wait or how many photos are left to sync.

Any of you experienced the same problem? Any suggestion?