@eNoch, looking at your original post, you have two errors after two different commands, but both errors are the same, and both reference uchime-dn-out/nonchimeras.qza even though that artifact is not used at all in the first command. That artifact should be usable as metadata, and I can in fact use it as metadata on my own machine after downloading it. for both qiime tools inspect-metadata and qiime metadata tabulate.
It is possible that your QIIME 2 install got messed up and doesn't know how to use it as metadata for some reason. Can you try running qiime dev refresh-cache and retrying your failed commands? If that doesn't work, can you remove and remake your conda environment and try rerunning your failed commands? If that still doesn't work, can you also send your table.qza so I can replicate the command
qiime feature-table filter-features \
--i-table table.qza \
--m-metadata-file uchime-dn-out/nonchimeras.qza \
--o-filtered-table uchime-dn-out/table-nonchimeric-wo-borderline.qza
exactly as you ran it?