Out of 2019 newbies (including the Chainsaw-Neo-Higuma batch), I have dropped 5/9 before their ending (Taisei, Kamio Yui, Saiyuki, Ne0lation and Higuma), 1 liking it (Chainsaw), 1 finding it decent at best (Tokyo Shinobi), 1 improving for me but mediocre (Beast) and 1 following just because of the mangaka but is horrific (Samurai 8).
Kamio Yui is even worse. The mangaka started it as a deliquent (but not serious) manga, then turned into a rom-com without ecchi, then became a pure gag with next to no romantic elements, then it shifted to ecchi, then turned to serious action with some occasional ventures to exposition random chapters.
I'm didn't make it all the way through ne0, Samurai, Beast, or Tokyo. I made it through Higuma and thought it was decent, but not amazing. I wouldn't have minded if it stuck around a bit longer. Saiyuki is starting to lose me, but since it's probably near the end, I'll stick it out. Chainsawman I read purely for Denji/Power shenanigans. I can honestly barely tell what's going on in those fight scenes half the time.
Kamio Yui is a wild ride. I truly can't figure out if I like it as a whole or not since you never know what you're going to get each chapter. Just when I thought it finally found its footing, this most recent chapter again randomly lounges the story elsewhere with no prior warning. I'm going to stick it out, but I wish it would've just stuck with being a double harem and balancing out the hijinks that result. Double Taisei is equally if not more unpredictable, but in a negative way. As others have mentioned, the author just seems to be haphazardly changing the whole plot of the series. I may continue peaking at it just to see what happens next.
Needless to say, the serializations from this year have bummed me out a bit overall. Samurai's 99% will sell well, even if its subsequent volumes each decline, and Chainsaw's improving steadily, but WSJ has been striking out quite a bit lately. With Soma ending, and World Trigger and Boruto (and Jimoto

) transferring out, I'm hoping they can turn things around eventually.