Site with root domain as default domain (ANAME) setup went offline

Hi

We have a Webflow site that is set up with the root domain vendanor.com as default domain (ANAME record as described by Webflow here, instead of the A records normally used). The site has been working fine since January 2021 with the Norwegian DNS provider Domeneshop, but we noticed today that the site was offline and the browser was returning a security error.

We immediately changed to the normal A record setup, and the site is now online again.

Question 1:
Is this root domain error due to a temporary error at Webflow or a permanent change in the Webflow hosting setup? Or can it be a problem with the DNS provider?

Question 2:
The client is concerned for any SEO/SERP ranking degradation since the site no longer is placed on the rood domain vendanor.com, but instead redirected to www.vendanor.com.

Anybody with any experience on this subject?