Issue with Keycloak and Cloudflare

I’m running Cloudflare and Keycloak.

I’ve secured a web site with Keycloak and I use Keycloak’s login forms, registration etc, and everything works fine except logging out.

What happens is, after I login through Keycloak, it redirects me to my website.

Here when logging out I redirect back to e.g.

But this actually get’s somehow blocked by Cloudflare and it returns a 520

Has anyone else experienced similar issues? What could cause this?