This is mentions of Apple in the source code, not contributions, and non-Apple people have added lots of support for Apple hardware over the years.

The recentness of this makes me wonder if this is Asahi contributions.

Apple is Berkeley Unix-based, while not actually Linux it's possible their contributions to open source have made it's way into Linux (me guessing, no real experience of either Linux or Mac).

Could also be that there's been work done to communicate with Apple specific products, again wild guesses but based on my perception of people working with Apple products is that there might be above average number of "edge cases" that needs addressing when communicating with those.