For clarification. Chapter 21.1 came out in 8th August (2 months ago), while chapter 21.2 came out in 12th of September (1 month ago). Depending on the difficulty, your efficiency, and how meticulous you want to be, scanlating a chapter can take anywhere from 1 to 50 hours (and I'm talking about full work hours, not work for 10 mins and then browse Twitter / chat on Discord). Alas, it's a lot of time, which is why we have only a select few series that we love the most that we scanlate.
With a full-time job and other commitments, we have a limited time window where we can work on scanlation, so a chapter could even take up to months to be ready with an active team working on it. FYI: it's an unwritten rule amongst scanlators that a series is considered "dropped" if there is a new chapter after the group's latest release and the group hasn't updated for 3 months. Releasing the next chapter within that time is considered "sniping." Obviously, it is up to you to decide on whether sniping is good or bad. To give you food for thought, on one hand, the readers benefit from having chapters earlier, but on the other, the sniping group is dismissing the other group's efforts and commitment (after all, if the other group was working on the same chapter, it would all be "meaningless" work as the readers would have already read it).
However, it's totally understandable that a reader is not aware of this, and, given the lack of context, might assume that the team has given up when they see "6 months ago" on MangaDex. I personally don't expect anyone to be proficient in "the ways of the scanlator," so I really appreciate it when some go through the trouble of checking the dates themselves to defend said group, even when it is unwarranted.