Starting Sept. 4, 2021, USCIS extended the time that receipt notices can be used to show evidence of status from 18 months to 24 months for petitioners who properly file Form I-751, Petition to Remove Conditions on Residence, or Form I-829, Petition by Investor to Remove Conditions on Permanent Resident Status. According to the USCIS webpage it was making the change from 18 to 24 months to accommodate current processing times for Form I-751 and Form I-829, which have increased over the past year.
The complete news can be accessed using the link below;
https://www.uscis.gov/news/alerts/uscis-extends-evidence-of-status-for-conditional-permanent-residents-to-24-months-with-pending-form