there are very few I just outright dropped and consider a 1/10
former strongest swordsman isekai is a manga that falls into that, starts fairly mediocre then halfway through it just keeps on getting worse with timeskips, the objective of the mc being ignored, side characters just standing there doing nothing because mc is made too op whenever the plot needs it and shit pacing with barely anything being explained (at one point there is a 1 year time skip in one of the main characters gets a double personality or two people inside her head or something which is just not explained, also one character of the previous ark is just gone)
most of the fight scenes are also incredibly scuffed, not really anything pleasant to look at and the backgrounds are 90% nonexistant with white space taking its place
read and dropped it recently so only one I remember the name of, its a shame that there are shitmangas out there like that one somehow not getting axed while other pretty good stories get it instead