GSC issues? (Flatliners)

[AndiFox]

I have several clients who seem to be ticking along just fine and for whatever reason, a complete flatline happens in GSC.
They see it and panic and I honestly don't have any answers.
I've never experienced it before.
It's happening on 9 different sites and they've all happened in the last 6-8 weeks.
Some of the accounts are under one account and some are on their own accounts.
I haven't done anything crazy.
It's just a mystery to me at this point.
Anyone else having the same issue?
Any hints?
TIA!

 

[JoyHawkins]

9/10 times I've seen this happen it's because the canonical version of the site changed. For example, the canonical version is now Website Domains Names & Hosting | Domain.com and you're looking at Website Domains Names & Hosting | Domain.com (no www).

 

[AndiFox]

9/10 times I've seen this happen it's because the canonical version of the site changed. For example, the canonical version is now Website Domains Names & Hosting | Domain.com and you're looking at Website Domains Names & Hosting | Domain.com (no www).

Ok.. interesting. I need to figure out if something changes and I didn't notice.
Thank you!

 

[Ana]

It’s nothing to do with canonical but the user has applied black hat seo without knowing. The page continues to slide until it’s repaired.