Rome's persecution of specific Israelites who have "τὴν μαρτυρίαν τοῦ Ἰησοῦ" was poetically documented in [Revelation 12:17] - "And the dragon was enraged with the woman, and he went to make war with the rest of her offspring, who keep the commandments of God and have the testimony of Jesus [Christ]." (12:17 καὶ ὠργίσθη ὁ δράκων ἐπὶ τῇ γυναικί καὶ ἀπῆλθεν ποιῆσαι πόλεμον μετὰ τῶν λοιπῶν τοῦ σπέρματος αὐτῆς τῶν τηρούντων τὰς ἐντολὰς τοῦ θεοῦ καὶ ἐχόντων τὴν μαρτυρίαν τοῦ Ἰησοῦ Χριστοῦ)...
But the NKJV recognizes the word "Χριστοῦ" was omitted by the Greek NU-Text and M-Text. [https://www.blueletterbible.org/nkjv/rev/12/1/t_conc_1179017]
The Textus Receptus word "Χριστοῦ" to [Revelation 12:17] may refer to the Testimony mentioned, although the addition of "Χριστοῦ" violates the commands of [Revelation 22:18].
Why did Textus Receptus add the word "Χριστοῦ" to [Revelation 12:17] ?