We have upgraded build.webkit.org to latest Buildbot (v2.10.1 released in 2021) (https://webkit.org/b/175056). Earlier it was running an ancient version of Buildbot, v0.8.6p1 (released in 2012). This is a brand new server. Buildbot doesn't support migrating data from old version. Old instance is accessible through https://build-old.webkit.org
Known issue: Login functionality is not enabled for everyone yet.