I think what @mikeone was implying (correct me if I'm wrong) is that:
Every time someone rolls out some new thing, some old thing breaks.
Another user reported login issues with Hotmail on a new phone, with same account continuing to work fine on the old one.
And then in morning the issue went away, it just started working.
So maybe -- just give it a bit of time, and see if the issue goes away.
And just in case:
1 - Please make sure that AquaMail settings -> network -> "Use DNS" is enabled (top item, is enabled by default)
2 - May be worth changing the incoming server setting in AquaMail from
imap-mail.outlook.com
to
imap.glbdns2.microsoft.com
The former is a "synonym" for the latter, which is the "real" server name. The change will save one iteration during DNS lookup, may help.
$ dig imap-mail.outlook.com
;; QUESTION SECTION:
;imap-mail.outlook.com. IN A
;; ANSWER SECTION:
imap-mail.outlook.com. 195 IN CNAME imap.glbdns2.microsoft.com.
imap.glbdns2.microsoft.com. 195 IN A 65.55.122.74