Question : Cloudflare tunnel, load balancer and old dns settings

I am trying the Cloudflare tunnel for demo.mydomain.comt. It’s easy to use and it works, but I have a problem with the existing domain name redirection in the DNS configuration menu.

I added the public hostname in Cloudflare tunnel settings "demo.mydomain.com" -> local service
The existing domain name with redirection to demo.mydomain.com configured in dns settings doesn’t work. ex : test.mydomain.com -> demo.mydomain.com.
This domain name redirection is not in the Cloudflare tunnel but in the dns settings and answers
“no webpage found on this url” but demo.mydomain.com works.

Is this the normal mode of operation ?How to make the old redirects active with the new Cloudflare tunnel configuration?

We also have redirection with LB. If we move this inside Cloudflare tunnel, current dns redirection to this lb works again ?
ex:

prod.mydomain.com --> loadbalancer cloudflare
one.mydomain.com --> prod.mydomain.com
two.mydomain.com -> prod.mydomain.com
...

thanks for your help