Chrome Web Store is phasing out support for new Manifest V2 extensions
Google has sent an email announcement to Google Web Store developers warning about new deadlines for Manifest V2 phase out. Starting from January 17, 2022, Chrome Web Store will stop accepting new extensions based on Manifest V2 with visibility set to "Public" or "Unlisted". Existing extensions will not be affected and you will still be able to publish updates. Moreover, this new restriction will start applying to new "Private" extensions as well starting from June of 2022.
This is quite a short timeline from Google considering that Manifest V3 still has many feature gaps compared to Manifest V2. If you are in progress of developing a new extension and are blocked from migrating to V3, you should provide feedback to the Google extension team in the official chromium-extensions Google group. Alternatively, maybe it's time to expedite the release of your extension, so you can at least publish updates after the January 17 deadline.
You can find the full Manifest V2 deprecation timeline here.