Question about Roots

Curious if anybody knows exactly how roots work now. I enjoy playing mostly supports. But I've noticed with the new root/stun system, adcs with free escapes are completely unstoppable. I root ezreal, he immediately uses his ability to flash away while rooted. Grab and pull tristana, then hit her with my knockup as blitz, she's stunned, knocked up, then flies away. Same with leona. Stun an ezreal, they use their flash away ability while stunned. It almost makes it worthless to even play any champ but afk healing supports anymore.

Every root or stun I use on an adc with a free escape, they are stunned, then use their ability to escape and end up 10 feet away still stunned/rooted. Blitz is practically worthless now. If you drag and pull someone your stun will do nothing to them, they either flash out of your hook itself, mostly ezreal who seems to have no limit on when he can use his escape. Or the second they land even though you hit them with the stun/knockup, they still flash away after being stunned.

Is this just a lag/glitch or is it working as intended where champs with free-flash abilities are just not able to be rooted/stunned anymore. I gave up playing leona since anybody I stunned just blinks away Her ult is an effort in futility. You ult an entire team, then watch half of them use free-flash abilites to immediately teleport away while -still stunned-. Been doing lux, same thing. I root an ezreal, and before I can even start throwing my other abilities at him, he's already used his flash while rooted to teleport away.