Since Yesterday, I managed to stay invisible on accident while eating pigs multiple occasions and was even able to reproduce it.
I was spamming the E button just to become invisible again as fast as possible while holding F to start eating, but instead, I skipped the decloaking animation completely and stayed invisible as if nothing happened.
This is also very interesting as I witnessed a lot of Predators lately that also skipped certain animations, like changing weapons and eating boars a whole lot faster than it is supposed to be.