Google search: about domain change

Hi,
Happy new year. We sell custom stickable wall photo tiles. Users can upload their photos via our mobile and web app. We will make stickable wall art prints and deliver to their door according to their uploaded photos.
Here's the question. We just changed our domain name to artivphototiles.com from https://phototileapp.com 50 days ago. We followed the google's advice to do this work. However, the ranking, exposure and click are still much lower than it used to be.
It's about 1/10 click number of the previous click number.
Could you please give me some advice?
Lesson learned: Do not change the domain...It will change google search rankings.