it doesnt matter how clearly telegraphed it is when you get qewaaqaaq she can simply gap close a massive amount of distance almost instantly by animation cancelling
as for sources, i only have what a few riven mains have said, and my own personal experience
before with the usual riven bs of eqwaa you are now stunned for .75 seconds before this meant that right before her 3rd q landed you could get out of with a dash or some such
HOWEVER. after they fixed the thing animation canceling for her was STILL improved because of how easy it is to now cancel AA animations this shaved crucial percents of a second to be able to then qaa and then 3rd q you without you having the ability to dodge it.
one credible source i can give is champion .gg which shows that after patch 6.20 (where the bug was introduced and then fixed post haste because it was broke as FUUUUUQQQQQQ) it shows a steady increase of win rate up to patch 6.23. now many factors can attribute to win rate however i am happy to think that as people got used to the new animation they got better with the combo and faster. and because there was less counterplay to the riven fast combo because you where simply stunned to long and the combo was to fast it allowed her to simply win more.
find a good riven and see for yourself look at the fast combo in patch 6.19 and then in patch 6.21
https://www.youtube.com/watch?v=40GwynGw3fo
the 2nd example is the one we are looking at here. it looks pretty normal right? takes right about 2 seconds to perform the full combo. which means that you are only stunned for alittle under half the time.
however the combo im talking about is the classic eqw where you animation cancel your way right up into there face and stun them so lets look at how long after the 2nd q it takes to actually smash them and hurt them. thats right it took about a entire second to perform just a qaa3rdq
giving you a grand total of .25 of a second to react to her which by the way she just unloaded her entire metaphorical nut onto you (and her passive is total BS) if you do not get out of the knockup in that time frame you wont have the chance to trade back as well as you might want (she literally wins trades by defaults if they are good enough)
however now in my experience you dont even GET that .25 of a second. it feels now like you dont get any time to counterplay her. i cant find any videos clearly demonstrating it, but alot of rivens just tell me "yeah its faster" and in my experience i have to agree
for a solid demosntration i got absolutely THROTTLED by a riven because my udyr pulled a bad gank, she is a good riven, oh look she got a free kill? now she can just straight up murder me because #balanced. but thats not the point. the point is that i USED to have the ability to vlad W before her 3rd q would hit in that scenario. however now i dont have that. multiple times yesterday when i fought that riven as vlad i simply couldnt no matter how hard i tried because the combo is that much shorter
thats firsthand experience from me take it as you wil