I see 2 separate questions in this thread.
First about the Java version compatibility: the current version of SonarLint requires a Java 11 runtime (and I see you are using Java 18 in your settings), and recent versions of SonarQube require a Java 17 runtime; however, the analyzed projects themselves can still use an older version of Java - recent versions of SonarQube and SonarLint will still happily analyze projects that use Java 7.
Second about the proxy: SonarLint currently does not honor the IDE settings (we have a ticket to address it). However, you can use the workaround described in this other thread and pass the proxy settings directly to the JVM’s network infrastructure.