TLDR
So what does community-maintained mean? Are they maintained by official VS Code team members or by unofficial distrbution-specific commnuity maintainers?
by unofficial / official distribution specific community maintainers (see further). Almost never is a package maintained by the people who make the software itself
Specifically this version https://archlinux.org/packages/extra/x86_64/code/ is Arch Official. Though it isn't MS Official.
This version https://aur.archlinux.org/packages/visual-studio-code-bin is NOT Arch Official. It is however MS recommended https://code.visualstudio.com/docs/setup/linux#_aur-package-for-arch-linux. Note that even though the AUR page says it's "official", it says it's an official binary version. Which means that the package claims it contains the official version (if you are to believe the word of the maintainer), but it is still on based on trust of the community maintainer.
Is there anyway to ensure packages maintainer are from official software team?
Yes. Look up https://aur.archlinux.org/packages/visual-studio-code-bin, look at the maintainer and check if this person is someone from the official team of the software. (I believe it isn't. Although since the package is endorsed by both Microsoft and Arch wiki, I would consider it safe)
Context
Packaging on Linux is a bit of a mess with many different people with different responsibilities. And you chose a specifically complicated example.
There are two jobs, roughly. Make the software and adapt the software to the distro (Arch Linux). These jobs are done by different people (often). E. g. vscode is made by contributors on https://github.com/microsoft/vscode. Arch's VS code package is made by "dcelasun". What does it mean to "make the package"? It means to write this file https://aur.archlinux.org/cgit/aur.git/tree/PKGBUILD?h=visual-studio-code-bin which is used to adapt the software to distro specific needs.
Now however there are usually two groups of packages on any distro. Official and unofficial ones. On Arch Linux official are packages in core/extra repository. On Debian-based distros official packages are the ones you can install with apt (WITHOUT adding any PPAs)
Now however what about the unofficial ones? Distros usually provide a way for users to distribute any package. These packages are by nature not official or checked by the official distro team. On Debian they are called PPA, on Arch they are called AUR.
You can probably infer the security implications yourself. Anything in official repositories is with high degree of probability safe. Anything in user/unofficial repository you need to check yourself.
vs code
Vs code is a bit of a mess because there are at least 3 versions of the software with different licensing and in different repos. See https://wiki.archlinux.org/title/Visual_Studio_Code
Basically the "Microsoft official" version of VS Code cannot be in the "Arch official" repositories, because of license. However the Open Source variant of VS Code can be and is in official Arch repositories.
There is furthermore one last "un-microsofted" variant of vs code, in AUR. That one is officially not supported by neither MS or Arch, but it is told to be more telemetry free.