The support for the following DHE cipher suites has been removed from WebRTC Datagram Transport Layer Security (DTLS) handshake, because those protocols are considered too weak. There are only a few uses of DHE at this time according to Mozilla’s Telemetry, so the compatibility risk of the removal should be very low.
TLS_DHE_RSA_WITH_AES_128_CBC_SHATLS_DHE_RSA_WITH_AES_256_CBC_SHA
Update: The DHE cipher support for general purposes has been removed with Firefox 79.