The list I provided was from 2017 and only a single anime of an entire season was mastered at 1080p. Even in 2018 and 2019 that's still typical. Maybe 1-2 serie

The list I provided was from 2017 and only a single anime of an entire season was mastered at 1080p. Even in 2018 and 2019 that's still typical. Maybe 1-2 series produced at 1080p with every other series being an upscale. Some seasons even have 0 series produced at 1080p. Instead of calling it a myth, try to find a season where a large number of anime were produced at 1080p as counter-evidence. Being upscaled and released on DVD or BluRay at 1080p (which most anime have been for most of the past decade) is not the same as being produced at 1080p. I wasn't aware of the two Gundam movies mentioned by fireattack, but I can't confirm they were mastered at 4k and aren't just upscales. So if you could name some of those 4k releases that would be helpful, especially if you can provide information as to them being mastered at 4k and not just upscaled to 4k.