Mystery solved. I looked for jingles in sound effects and they are there, although there are less than before. Dream and fantasy, a jingle that I especially liked, for example, is not there anymore.
But jingles, divided into categories, were under Music before. Putting them in sound effects is very new and rather messy. I edited a video three weeks ago, before all the upgrades I did, and all jingles were in the music library.
I guess Apple wants to reserve that space for sales now. I wonder what will be their excuse. Something as preposterous and untrue as their claim that iPhones don't come with chargers anymore in order to save the environment. Meanwhile, millions of people who are buying iPhone for the first time will have to buy a charger separately, which means one extra paper package , extra fuel used in the delivery etc.