Like Catholicism, both the Eastern and Oriental Orthodox (which includes the Ethiopian Church) base their OTs on the Septuagint. As others have said, there were different versions of the Septuagint in the early church. Psalm 151, 3 & 4 Maccabees, 2 Baruch, 3 & 4 Esdras, Jubilees, the Prayer of Manasseh, & others were in some of these early versions of the Septuagint. Oxyrhynchus included 23 early versions of the Septuagint & at least 1 Old Latin (the version of Latin before the Latin Vulgate), which included some of these books, which was also prior to the fourth century church councils which did not include some of these books. 1 Esdras (sometimes called 3 Esdras), which are the additions to Ezra-Nehemiah, were originally in the fourth century councils of Hippo & Carthage, because they were included in these early versions of the Septuagint. But it was not included in Jerome’s Vulgate (even though it did show up in later versions of it), nor was it in the later Ecumenical Councils of Florence (1441) & Trent (1546). Protestants don’t include any of these books, as well as the Deuterocanon, because it is believed that although the NT cites or alludes to most of the Deuterocanon as well as many of these Apocryphal books, they never cite them specifically as Scripture like it does with the books in the Hebrew Bible.