Is it okay to paraphrase other authors' literature reviews? I am currently writing a literature review for my bachelor thesis and I am not sure if what I am currently doing is acceptable.

My approach right now is to look at about 10 different literature reviews(from different papers) regarding the same topic and take one or two sentences or sometimes a paragraph from each of the literature reviews and put it in my thesis. Afterward, I synthesize the sentences I've collected from other authors' literature reviews and form a new paragraph. Lastly, I paraphrase the new paragraph and cites the original contributors behind the sentences.

Is this considered plagiarism?
Though it is a subtle difference, it seems that you might be rewriting sentences in your own words rather than paraphrasing authors’ ideas. It is difficult to assess your work without specific examples, but it sounds like it is bordering on plagiarism. Others may or not consider this plagiarism, but either way it is bad practice.

Since it is certainly easier to accidentally plagiarize using your method, I recommend taking notes on the pieces you are reading (rather than taking direct quotes/sentences) and paraphrasing your own work. Not only will this lead to a greater understanding and coherence of writing, it will also negate (most) plagiarism concerns.

And as always, cite, cite, cite.