Parallel
Hebrews 12:27
Nestle 1904 Greek New Testament · Berean Standard Bible
τὸ δὲ Ἔτι ἅπαξ δηλοῖ τὴν τῶν σαλευομένων μετάθεσιν ὡς πεποιημένων ἵνα μείνῃ τὰ μὴ σαλευόμενα
The words “Once more” signify the removal of what can be shaken—that is, created things—so that the unshakable may remain.