Giulia's (tech) features are 5 years behind the competition, not enough advertising and wrong advertising, dealer network isn't great, brand image isn't great, saloon segment is in decline, models like Giulia (and Stelvio) are therefore still pretty unknown to general buyers in premium segment.
Audi just intruduced face-lift of their A4 model (after a small face-lift last year), which was brought to the market around the same time as Giulia (2016/17), and even back then it had much more technologically advanced features. And even if face-lift looks crap and like they just stuck a Hyundai face to the Audi body, it shows how hard working the German brands are. BMW just launched the new 3 series, so Mercedes, aware of that, prepared a C-class face-lift last year, and Audi made a face-lift right after, just to slow down sales decline. Even Jag made a face-lift when BMW made new 3 series.
It seems everyone is working hard and doing their job.
Alfa will introduce MY2020 Giulia with some updates in Q3 this year, but it seems it will still stay noticably behind its rivals on everything else but driving dynamcs and styling. Sad sory indeed. In the end sales slide is not really that surprising, it is their own fault for being lazy the last 3 years, and introducing only various trim/colour versions.