Wth dude i think something wrong to your eyes sorry but many knetz praise yeri's acting even non rv fans. But…
true regular viewers like us are no acting master we just consume content that we pay for and we entitled to have our opinion as everyone should but judging by your experience or intelligence you might have trained people in the past whenever you have seen not so good acting , just assuming.
Great plot and pacing only downside Female Lead's acting , they could have casted someone better .ML is also okay not too good , however surprisingly he's good at doing emotional scenes but the actress playing ML's sister nails her role splendidly in her limited screen time and the guy playing kim sin u too.
story ,camera work looks amazing ost too support cast looks natural too ,ML who looked kindaa stiff showed acting skills in ep3 when his story unfolds , FL on the other hand don't seem to be doing justice to her role may seem a bit annoying at times has huge room for improvement again people should focus more on plot ; seems like a 7.8 Drama