Cloudflare email: rcpt to rejected

this is not related at all to my own cloudflare usage. I am writing an email test service and while testing a new version I encoutered a customer of cloudflare that is using cloudflare email (route*.mx.cloudflare.net).

The dialog goes like this:

220 mx.cloudflare.net Cloudflare Email ESMTP Service ready
EHLO mail.lindenberg.one
250-mx.cloudflare.net greets mail.lindenberg.one
250-STARTTLS
250-8BITMIME
250 ENHANCEDSTATUSCODES
MAIL FROM:<***>
250 2.1.0 Ok
RCPT TO:<***> 
502 5.5.1 Unrecognized command. ***
RSET

on RSET cloudflare closes the connection rather than replying 250 OK. Both the unrecognized command and the connection close are unexpected. *** indicates where I redacted information.

Can you please clarify why?