I saw the first season of the anime on Netflix and I loved it. Afterwards I saw the successor Root A until the 3rd or 4th episode and I did not like it at all, so I canceled it. A little later I heard that the sequel (after Season 1) in the manga is completely different. Is that correct? (please no spoilers)
Yes that's true.
For example, Season 2 is not like the manga at all.
Thank you. Then I can always look forward to the manga, if I get it.
Well, season 2 is NOT like the manga I would not sign after watching the anime twice and reading the manga as well. Only the end, or The last episodes are very different from the manga.
Season 3 and 4, so Tokyo Ghoul: re, however, use the full manga, even if there are few scenes missing.
Root a is the adaptation of the second half of the Tokyo Ghoul Manga, so the prehistory to Re.