It'd be disingenuous to say PUBG is getting C4 today. Since its launch in January, the ultra-small Karakin map has had "sticky bombs" littered all around it. They're meant for breaching walls, but enterprising players will chuck them at others with hopes that the extremely small blast radius will cause some damage.
But, PUBG is getting a different spin on C4 today, one that's a lot more powerful and a lot more latent. PUBG's 7.3 update adds C4 to all the non-Karakin maps (Erangel, Miramar, Sanhok, and Vikendi) as a throwable explosive that takes 16 seconds to detonate. Unlike real C4, there's no way to detonate on cue. It's just 16 seconds of ever-increasing beeping until everything in close proximity gets blasted to bits.
It sounds like you'd have to be geriatric to get hit with C4. Well, that's not necessarily the point. It's more of a tool for flushing other players out of cover. The blast radius is 25-meters wide and the explosions penetrate cover. If someone throws C4 in your vicinity, you need to move. If you're so pinned down that C4 kills you, you were trapped between a rock and a hard place (or between a bomb and a bullet).
Besides these revamped extremely lethal frag grenades, PUBG overhauled the way vehicle damage works. Now, vehicles take full damage on shots to the engine area, but only 75 percent damage on the body and 50 percent damage on the roof. Also, there's more of a grace period between a vehicle catching on fire and when it explodes. It'll now blow up after 5 seconds. Lotta stuff blowing up in this update!
The PUBG site has the full list of 7.3 changes if you're so inclined. You should have plenty of time to read if while waiting for the C4 to detonate.