I doubt it has anything to do with the direct cost of maintenance. Google has a tendency to introduce multiple products that serve similar markets, as the article cited with Podcasts and YouTube Music. They have to cut the cruft eventually. Given the numbers cited in the article (23% listen to podcasts through YouTube Music, 4% through Podcasts), YouTube Music made more sense from the business perspective. I would imagine that is especially true when you consider that they can promote more products through YouTube Music.

That said, I somehow doubt that many people are going to transition from Podcasts to YouTube Music. There are too many alternatives out there, alternatives that would likely reflect the interests of Podcasts users better. Heck, nearly three quarters of podcast consumers are already using those products.