This is a problem that should have been solved the moment you typed the second entry. Manually filling genres for the same artist across thousands of rows is not a workflow, it is a tax on your patience. The good news is that the solution is simpler than you think, and it does not require learning a new programming language or buying a plugin.
What you need is a straightforward lookup formula. In Excel, `VLOOKUP` or `INDEX/MATCH` can scan your existing data, find the first instance of "Artist 1," and return the genre you already typed. For your specific case, `XLOOKUP` is even cleaner if you are on a recent version of Excel. It will search your Artist column for the name in the current row, then pull the genre from the first match it finds. That means Song C will automatically fill "Indie Rock" because Artist 1 already has that value somewhere in your sheet. One formula dragged down the column, and you are done.
There is a catch worth noting. If an artist has two different genres listed in different rows, say, one song tagged as "Indie Rock" and another as "Indie Folk", the formula will only return the first match. That might be fine for your current library, but if you want consistency, consider building a small lookup table on a separate sheet. List each artist once with their correct genre, then use `XLOOKUP` against that table. It takes ten minutes to set up and eliminates the ambiguity entirely. Either way, the core principle holds: you have already done the work of assigning genres once. Do not do it again.
This is exactly the kind of friction that a spreadsheet should remove, not create. Traditional tools have long forced users to choose between manual tedium and complex workarounds. An AI-native approach would go further, it could recognize that "Artist 1" already has a genre in your sheet and offer to fill it before you even finish typing the artist name. That is the direction we are moving: tools that understand your data well enough to finish your thoughts. For now, a simple formula gets you out of the weeds. Use it, reclaim the hours you were about to lose, and get back to listening.