Linode domain became unreachable

I use a Linode to run a Nextcloud AIO instance, accessed through a subdomain on a domain that I own. That domain is registered with Namecheap, and the Linode nameservers were added to the CustomDNS.

A few days ago, I made a mistake and mapped that domain to Squarespace for a website. Within a few minutes, my Nextcloud server became unreachable.

I realized the mistake, and changed the CustomDNS back to the Linode nameservers, but my Nextcloud instance remained unreachable. I recreated a Domain in Linode with the same details. But it remains unreachable.

Any idea how I could resolve this problem? Your help is much appreciated! Thanks!