As @Annieb said, it’s always been all-or-nothing. You have to have space for both the food and recruits, otherwise a warning pops up that you’ll lose them if you decrease the training.
Plenty of old references confirming this is a longstanding behavior can be found, here’s one random example from March 2018, of someone acknowledging that’s how it works, and from a post lamenting that if you click too quickly it’s easy to lose resources: