If you became a Lawful Permanent Resident ("Green Card" holder) at any time during 2014, then as of January 1, 2021, you will be considered a "Long Term Resident" by the IRS and maybe subject to additional reporting requirements and an expatriation tax, should you decide to surrender your status in the future.
Additionally, even if you became a Green Card holder at any time and are no longer living in the U.S., whether or not your Green Card has expired, you are still required to file taxes in the U.S. This is true, even if you are only a Green Card holder for a few days within a given year.
If you intend to give up your green card status, there is still time to do so before the end of the year, either to prevent becoming a Long Term Resident or in order to not to have file taxes going forward. However, it is very important that you comply with the IRS and USCIS guidelines, otherwise your attempt to surrender maybe delayed or ineffective.
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.