Microsoft Word Remote Code Execution Vulnerability

According to the CVSS metric, the attack vector is local (AV:L). Why does the CVE title indicate that this is a remote code execution?
The word Remote in the title refers to the location of the attacker. This type of exploit is sometimes referred to as Arbitrary Code Execution (ACE). The attack itself is carried out locally.
For example, when the score indicates that the Attack Vector is Local and User Interaction is Required, this could describe an exploit in which an attacker, through social engineering, convinces a victim to download and open a specially crafted file from a website which leads to a local attack on their computer.

According to the CVSS metric, successful exploitation of this vulnerability could lead to some loss of availability (A:L)? What does that mean for this vulnerability?
The performance can be interrupted and/or reduced, but the attacker cannot fully deny service.

Is the Attachment Preview Pane an attack vector for this vulnerability?
Yes. The attachment Preview Pane that is accessed when a user clicks to preview an attached file is an attack vector; however, the email Preview Pane itself is not.

Security updates
16.0.5413.1001 — https://support.microsoft.com/help/5002494
16.0.5413.1000 — https://support.microsoft.com/help/5002501
https — https://docs.microsoft.com/en-us/officeupdates/microsoft365-apps-security-updates
16.77.23091003 — https://go.microsoft.com/fwlink/p/?linkid=831049
16.0.5413.1000 — https://support.microsoft.com/help/5002497