Did they send you a paper notice in mail to inform about cancellation or was it an online notice?
My Naturalization interview was scheduled for April 3, 2020 and initially they had planned to stay closed until April 1, 2020 which later was extended to April 6, 2020. I had called the USCIS contact center and I was told that if my interview is cancelled, I will receive a notice in mail. I waited till March 26 and called again because I had not received any notice in mail except two generic Emails and a text message from USCIS stating that they had cancelled and will reschedule when possible.
This time the representative told me it could be either in mail or an online notice.