Early Evidence for Mark 16:9-20: Irenaeus (who lived from 125 or 130AD to 202AD) quoted Mark 16:19 (between 174-189AD, and Mark 16:19 is part of Mark 16:9-20) in his book "Contra Haereses Liber Tertius" ("Against Heresies, Book Three") and was alive earlier than all currently alive manuscripts, and earlier than Vaticanus & Sinaiticus' omission of Mark 16:9-20. Irenaeus also mentioned he was near the end of the conclusion of the book of Mark when Irenaeus quoted Mark 16:19👇.

In Old Latin: In fine autem Evangelii ait Marcus: Et quidem Dominus Jesus, postquam locutus est eis, receptus est in caelos, et sedet ad dexteram Dei; (Contra Haereses Liber Tertius, Chapter X, [Paragraph] 5).
https://archive.org/details/thirdbookstirena00irenuoft/page/n38/mode/1up

In English: "Also, towards the conclusion of his Gospel, Mark says: ‘So then, after the Lord Jesus had spoken to them, He was received up into heaven, and sitteth on the right hand of God.’ " (in Ante-Nicene Fathers page 426, see Against Heresies, Book 3, Chapter 10, Paragraph 5). https://archive.org/details/antenicenefather01robe/page/426/mode/2up

This proves that:
1) Irenaeus (who was born in 202AD between 174 to 189AD) quoted Mark 16:19 as per his
2) The disciple Mark, who wrote the New Testament's book of Mark, recognized and affirmed Mark 16:9-20, Mark 16:19, and all of the book of Mark as inspired Scripture
3) Irenaeus had a copy of the whole book of Mark before him, as Irenaeus stated he was near the conclusion of Mark, which is leads to the last established fact:
4) That Irenaeus saw, knew and recognized Mark 16:9-20 as inspired Scriptures, in order to quote Mark 16:19 in the first place

Also, Irenaeus wrote in both Old Latin and Greek, as his own book, in Chapters 1, 3, 4, 10, 11, shows large paragraphs and sentences of Greek and Old Latin words right below each other in many pages of his book, Contra Haereses Liber Tertius. This proves Irenaeus read both both Greek and Latin manuscripts and had copies of Mark 16:9-20 (in fact, Irenaeus admitted had the whole Gospel of Mark, including its conclusion, in front of him by saying "Also, toward the conclusion of his Gospel, Mark says"[English translation]/"In fine autem Evangelii ait Marcus" [Old Latin words").

KJB preserves Mark 16:9-20 and Mark 16:19, while the modern versions cast unbiblical doubt on Mark 16:9-20 being God's inspired words.

Anyone who claims "Mark 16:9-20 is not Scripture" is either decieved, willingly ignorant of, and/or is parroting and reusing false, unproven claims from evil false teachers (such as James White) while not researching the large amount of evidence for Mark 16:9-20 and its authenicity.

Mark 16:9-20 IS INSPIRED Scriptures. Do not let anyone deceieve you to believe otherwise.