If you don't want to lose your Google Maps timeline data when you change devices, you should turn on data backup. Google Maps Timeline stores user data on the device, so if you change devices, that data will be lost. With Google Maps timeline cloud backup enabled, all data is saved. Below are instructions for backing up your timeline on Google Maps.
Instructions for backing up timeline on Google Maps
Step 1:
The user clicks on the account avatar and then selects Timeline in the menu displayed.


Step 2:
Display notification as shown, friend Click Continue for the next operation. At this time the user Click on the cloud icon to enable backup of Google Maps timeline data. Next you are asked Enter your Google account password.
Step 3:
Now you need it Activate backup mode to use. Display notification interface, friend Press On below to enable backup of Google Maps timeline data.
So we have enabled Google Maps timeline backup on this device. And when you log in with the same Google account on another device, the timeline is synchronized.
Step 4:
If you don't want to back up your Google Maps timeline anymore, you just have to Turn off backup feature okay.