Heroku: unable to resolve DNS for server

I bought a myapp .app domain with OVH. I've also bought a Heroku hobby dyno in order to have a secure subdomain for my api (https : // www. server. myapp. app instead of https: // www. myapp. heroku .app).

In Heroku's dashboard/settings, I've added the domain server. myapp .app and copied the generated DNS target provided by Heroku. It looks like: hello-world-5fghjofz765h .herokudns
.com.

Then, I added a CNAME record in OVH's DNS zone panel. The name is server.reapr.app. But when validating the entry, I notice the generated domain has an additional . in the end: server.reapr.app. OEM Arabic

Is it normal? Should I enter the same name with a final dot in Heroku too?

Next. I added a CNAME record in my DNS zone panel.

When copy/pasting the DNS target in ovh, ovh claims that this is a relative notation that will point to hello-world-5fghjofz765h .herokudns .com. myapp .app..

They say I can add a . in the end to make this notation absolute and point to hello-world-5fghjofz765h. herokudns. com.. I don't understand what it means.

In any case, the DNS target is not strictly equal to the DNS provided by Heroku. There is either an additional . or a myapp .app. in the end of the url.

Anyway, I've tried both options. In each case, Heroku says they're unable to resolve DNS for server. The final error is: 1 domain failed validation.

How to fix this? I'm paying for a dyno I can't even access.

EDIT: The ovh DNS Zone. I own the domain www. myapp .app (myapp is a random name for this example, and is hidden by a black rectangle on the images below).
!J6Irt|690x116
The heroku subdomain settings:
!ue23R|689x196