representation of a nuc conversion do not point a conversion on the genome

[huzuner]

Hello,

For our research, I have been using resources from Nextstrain and I encountered an ambiguity that I wanted to ask about.

I am currently working on the tabular file for nuc conversions belonging to Nextstrain clades (https://github.com/nextstrain/ncov/blob/master/defaults/clades.tsv). I have been assuming that the clades.tsv represents nucleotide conversions, so they should inform about a nucleotide change compared to the reference genome.
However, I noticed that one of the conversions listed there, 22F nuc 15461 A, already points to A on the reference genome (NC_045512v2). Does this have an intended purpose or do I misunderstand the concept?

Thank you in advance for your response.