https://www.bing.com/search?q=SEC_ERROR_REVOKED_CERTIFICATE There is security software like Avast, Kaspersky, BitDefender and ESET that intercept secure connection certificates and send their own. https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can https://support.mozilla.org/en-US/kb/firefox-and-other-browsers-cant-load-websites https://support.mozilla.org/en-US/kb/secure-connection-failed-error-message https://support.mozilla.org/en-US/kb/connection-untrusted-error-message [https://support.mozilla.org/en-US/kb/websites-dont-load-troubleshoot-and-fix-errors?redirectlocale=en-US&redirectslug=Error+loading+web+sites Websites don't load - troubleshoot and fix error messages] http://kb.mozillazine.org/Error_loading_websites [https://support.mozilla.org/en-US/kb/what-does-your-connection-is-not-secure-mean What do the security warning codes mean]

This test page indicates the certificate was revoked as of May 30, 2020: https://www.ssllabs.com/ssltest/analyze.html?d=clcmv.com.ph&latest Firefox on desktop uses OCSP, which can check certificate revocation in real time. Due to bandwidth constraints, Firefox for Android uses a CRL (Certificate Revocation List) that is updated from time to time. I don't know why this certificate is not on the list. Maybe it is not an issuer that participates in CRL lists?

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