The Catholic Church does not reject any part of the LXX. The Catholic and Orthodox Churches might have a different idea of what exactly the LXX is. There is no “official” definition of the LXX, and there are many variants. The Catholic Church accepts the variant that was widely in use in the Western regions during the 3rd-5th Centuries. Various Orthodox Churches accept slightly different versions of the LXX which might have been in circulation in the East.
Nobody really knows which books were in the Septuagint at Jesus’ time. We know almost definitely that Tobit, Judith, 1 & 2 Maccabees, Baruch, Wisdom, and Ecclesiasticus (Sirach). Those were included in almost all the manuscripts. But since there was no “standard” version of the Septuagint, because there was no printing press, different manuscripts have more books than just those 7.
Different regional traditions trust different manuscripts. For example:
The Greek and Russian Orthodox Churches recognize the following:
Prayer of Manasseh
Georgian Orthodox Churches include:
4 Maccabees (which is only accepted as canonical in the Georgian Orthodox Church)
The Syriac Orthodox tradition includes:
The Apocalypse of Baruch
The Letter of Baruch
The Ethiopian Biblical canon includes:
Sorry if this doesn’t fully answer your question. Hopefully someone more knowledgable on the subject will come along.