Hello,
From Melbourne, Australia, I am reporting similar problem of eufy cameras cracked.
This morning I realised the front camera was like dirty on one side, I went home and inspect… and realised it was cracked from inside.
I have contacted Appliancesonline where I bought them last July 2019 (not even one year) … waiting for them to reply.
I am negatively surprised by that. All four cameras I bought have been ALWAYS kept protected by rain,wind,humidity and direct sun since I have installed them under roof, awning and strategic point.
I will have to check the remaining two tomorrow since the second one was not giving issues but it is clearly cracked without affecting directly the recording but I think once it is cracked, it is over. It will affect the recording.
This happened overnight for one camera, at 4:40 AM it was good, and at 5:30 AM, when I went to work, the camera was already bad but just noticed in the afternoon when I was checking movements.
Anker, may I know if are you going to replace all four, please? Did you fix this problem?
These cameras were actually good and stable (no issues to be honest) but this issue has ruined everything 
, I have pictures and video recordings to prove I am telling the truth and to better understand the issue.
thanks