I would honestly like it if there there is a warning/popup/alert that shows up which tells you that (x) of your pets are going to get released due to full stables. It will be best if this warning/popup/alert shows up around, say, 3-5 days before the pet turns into an Adult. It can show up in your mail, or maybe when you visit your Stables/Hatchery. This will be helpful, since I don't usually check my hatchery/stables that much anymore and I obviously want to know when I need to clear out some pets to make room for new ones.

I'd support if it was a pop-up. I really would rather no more notifications come in the form of mail, it's already clogged up enough by daily fest goals