Banding in JPEG gradients

I recently discovered that banding has started appearing in smooth color gradients when saving JPEGs in Adobe Photoshop. Naturally, I always save at maximum quality—12 out of 12. If I save as an 8-bit TIFF and then convert to JPEG using FastStone, I can select RGB as the photometric type in the save options; furthermore, I don't necessarily have to choose 100% quality—which would result in a 40 MB file for my example—since 95% is perfectly adequate for me, yielding flawless gradients and a file size of 16 MB, matching what Photoshop produces at its maximum quality setting (12 out of 12). Samples are here: https://disk.yandex.ru/d/7mPxpYfAsDOR7g