XOAUTH2 (aka "modern authentication") for IMAP does not work for some "*@outlook.com" accounts

Question

Microsoft announce support for XOAUTH2 authentication year ago and it works of Office/Microsoft 365 subscription (at least to my company subscription).

But for outlook.com accounts it works only for a selected accounts.

I have two outlook.com accounts, say "old@harsh.com .com" created years ago and "new@harsh.com .com" created recently.
And IMAP connection for "new" is working ok, but for "old" responded with "NO AUTHENTICATE failed."
I checked transcript and saw that accounts use different servers:

old@outlook.com
~~~
* OK The Microsoft Exchange IMAP4 service is ready. [UwBHADIAUABSADAANgAwADEAQwBBADAAMAAyADIALgBhAHAAYwBwAHIAZAAwADYALgBwAHIAbwBkAC4AbwB1AHQAbABvAG8AawAuAGMAbwBtAA==]
unbase64(Uw....) is SG2PR0601CA0022.apcprd06.prod.outlook.com
...
fsp04 AUTHENTICATE XOAUTH2 ....
fsp04 NO AUTHENTICATE failed.
~~~

new@outlook.com
~~~
* OK The Microsoft Exchange IMAP4 service is ready. [UwBHADIAUABSADAAMQBDAEEAMAAxADUANgAuAGEAcABjAHAAcgBkADAAMQAuAHAAcgBvAGQALgBlAHgAYwBoAGEAbgBnAGUAbABhAGIAcwAuAGMAbwBtAA==]
unbase64(Uw....) is SG2PR01CA0156.apcprd01.prod.exchangelabs.com
...
fsp05 AUTHENTICATE XOAUTH2 ....
fsp05 OK AUTHENTICATE completed.
~~~

Additionally, SMTP XAUTH2 authentication works for both "old" and "new" accounts w/o problem

Can i get some comment from outlook.com / exchange team - it is normal? Is the "modern authentication" not rolled to all "outlook.com" accounts yet?

---

Question was moved to the outlook.com forum