Apple started moving traffic off 3rd party CDNs to their own CDN six years ago. This is not a new development. 

Also, I see no issues with an ARIN whois lookup for that prefix.

~ % whois 17.0.0.0/8
% IANA WHOIS server
% for more information on IANA, visit http://www.iana.org
% This query returned 1 object

inetnum:      17.0.0.0 - 17.255.255.255
organisation: Apple Computer Inc.
status:       LEGACY

whois:        whois.arin.net

changed:      1992-07
source:       IANA

# whois.arin.net

NetRange:       17.0.0.0 - 17.255.255.255
CIDR:           17.0.0.0/8
NetName:        APPLE-WWNET
NetHandle:      NET-17-0-0-0-1
Parent:          ()
NetType:        Direct Assignment
OriginAS:      
Organization:   Apple Inc. (APPLEC-1-Z)
RegDate:        1990-04-16
Updated:        2017-07-08
Ref:            https://rdap.arin.net/registry/ip/17.0.0.0
...
...

On Thu, Sep 24, 2020 at 11:41 AM Mike Hammett <nanog@ics-il.net> wrote:
Breaking from current CDN infrastructure without reasonable accessibility to the new CDN is a problem.



-----
Mike Hammett
Intelligent Computing Solutions

Midwest Internet Exchange

The Brothers WISP


From: "Denys Fedoryshchenko" <nuclearcat@nuclearcat.com>
To: nanog@nanog.org
Sent: Thursday, September 24, 2020 9:27:07 AM
Subject: Apple moved from CDN, and ARIN whois

Hi,

Interesting, it seems AS6185 moved traffic from all CDN to their own
content network.
I noticed big spikes in traffic and complaints about slowness, figured
out, Apple content (especially updates) are not coming from a numerous
co-hosted CDN, but became "live",
congesting upstreams.
So much efforts on collocating endless CDN in premises to keep things
closer to users and handle traffic surges, and yet again, some companies
keep inventing their own.

P.S. I dont know if it is bug, but whois at ARIN return "No match found
for n + 17.0.0.0/8" for 17.0.0.0/8,
but works fine for single ip from this range, like 17.0.0.0, and returns
info about 17.0.0.0/8