Cloudflare chaging header Case

My Origin Server header are

HTTP/1.1 200 OK
Date: Sat, 07 May 2022 17:57:08 GMT
Server: Apache
Upgrade: h2,h2c
Connection: Upgrade
Last-Modified: Fri, 10 Jul 2020 10:07:09 GMT
Accept-Ranges: bytes
Content-Length: 115487
Timing-Allow-Origin: *
Cache-Control: max-age=2678400, must-revalidate
Access-Control-Allow-Origin: *
Content-Type: image/jpeg

but Cloudflare chaging some header from proper case to lower case why?

HTTP/1.1 200 OK
Date: Sat, 07 May 2022 18:02:09 GMT
Content-Type: image/jpeg
Content-Length: 115487
Connection: keep-alive
last-modified: Fri, 10 Jul 2020 10:07:09 GMT
timing-allow-origin: *
Cache-Control: max-age=2678400, must-revalidate
access-control-allow-origin: *
CF-Cache-Status: EXPIRED
Accept-Ranges: bytes
Expect-CT: max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
Strict-Transport-Security: max-age=15552000; includeSubDomains; preload
X-Content-Type-Options: nosniff
Server: cloudflare
CF-RAY: 707bdd70d8735782-IAD

Whilst I wouldn’t particularly be able to tell you why it does that, is it just curiousity or are you encountering any issues because of it?

Header names are, by spec, case-insensitive (and in HTTP/2, should be lower-cased entirely).

Just as in HTTP/1.x, header field names are strings of ASCII
characters that are compared in a case-insensitive fashion. However,
header field names MUST be converted to lowercase prior to their
encoding in HTTP/2. A request or response containing uppercase
header field names MUST be treated as malformed