I was shooting this guy, and on my behalf his armor and health didn't deteriorate. I think it's not a SAMP issue.
5:37
https://www.youtube.com/watch?v=l4TcyJzj_2M
Not a bug, lag or desync issues. Maybe you were lagging or the cop was lagging. As it shows on your screen that the player did'nt lose any health but maybe on the cop's screen he was losing health.