Conversion of Ensembl Gene Ids to Uniprot Ids

Hi, I'm a computer scientist with no knowledge of biology. I'm working with protein-protein interaction and didn't understand how to make a conversion.

Usually, I use the UniProt Id conversion page to convert Ensembl Gene Ids into UniProt Entries or Ids. However, several mappings fall into the case: 1 Ensembl id I get multiple rows/UniProt entries id. My question is: how can I choose safely a unique entry? Should I filter by something like reviewed or unreviewed entries?

The same happens when I try to convert gene names to UniProt ids. I understand that a gene can make more than one protein but, for the best of my knowledge, that case should be rare, no?

Thanks in advance, I'm struggling with that.