I worked on an extension deployed to Firefox and Chrome, initially, Firefox was taking around two days to accept changes, while the app was being released on Chrome pretty fast (taking a couple of hours), at that time, the extension was built in TypeScript without minification, my guess is that this lack of minification helped to get changes accepted on Chrome.
After some time, the extension was migrated to Scala (thanks god for scalajs), as Firefox asks for the source code while submitting updates, I guess this change was not a problem, it was being accepted on Chrome as well.
Some updates later, Chrome rejected an update with no clear reasons (it was a 1 line change to fix a bug), after trying to fix everything we could and until it got accepted, this review process took more than 3 weeks!
After the first rejection on Chrome, most updates started taking days to get reviewed (a week long was common), the last update was rejected again with no clear reason, i tried contacting support (good luck trying to find the email, not unusual in google products) and even offered to share the source code or even open source it to simplify the review process, they didn't commented on this and just gave some hints about the rejection.
I have the feeling they flagged our extension since the first rejection and that causes the delays but I don't what could have possibly cause your delays.
You can try contacting support on chromewebstore-dev-support [at] google.com
Thank you for reaching out to us. I understand that it is taking awhile for the review to be completed and approved.
Please note that both new item submissions as well as updates to existing items are subject to automated system checks and may be flagged for manual review. Review times vary; some reviews complete in a few hours, others take many days, and in some cases a review can take several weeks, depending on review complexity of each item.
This documentation  will be helpful to get an understanding on what items our review team considers for manual review.
However, I noticed checked your extension and it's published to the Chrome Web Store successfully. Let us know if you need help with anything else. We greatly appreciate your understanding.
Chrome Web Store Developer Support Team