As of this morning LibreOffice 6.4 was branched from master and the beta release tagged with those LO 6.4 Beta binaries expected out shortly.
LibreOffice 6.4 remains on schedule for releasing either at the end of January or first days of February. The LibreOffice 6.4 Beta release is making it on time while this branching also marks the hard feature freeze for the next installment of this open-source cross-platform office suite.