In the empirical sciences, one can commit academic malfeasance by fabricating data, etc. Is there any form of academic malfeasance in mathematics?

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given the ‘a priori’ nature of math, is there anything about which a researcher can be dishonest about such that it invalidates their results? I understand that plagiarism might be a thing, but that doesn’t invalidate the plagiarized results’ validity. Is there any equivalent to fabrication of data, misrepresentation of sources, etc?