Version 2.4.3 is a minor version to fix a regression in ./gradlew downloadApolloSchema introduced in 2.4.2. The task would fail asking for a service even if schema and endpoint were correctly passed (See #2728 for more details).
Many thanks to @nicusorflorin for spotting this!
Other included fixes:
[SDL] better handling of string escapes (#2729)
[KMP] added a 'timeoutMillis' parameter to ApolloHttpNetworkTransport (#2680)