I agree with
@Bad_Vader to some extent.
Sure, it would've been better had the people who did this chapter told LunaLotusScans about it, and maybe worked on the following chapter (ch22) rather than this one (ch21) since LunaLotusScans had already been working on it for a while, and then release the chapter not long after this chapter's translation by LunaLotusScans is released.
That would've been the best way to go about it.
However, on the other hand, maybe the people who did this chapter thought that this chapter wasn't being worked on due to not noticing that LunaLotusScans has different translators take care of different series. For example, Viopera is the one taking care of this series, and since the last chapter (regardless of which series) Viopera released, Lxpiz and Rosenna have released several chapters of other series.
As such, if the people who did this chapter didn't notice the "different translators for each series" thing, it's a genuine possibility that they thought this series was no longer being worked on as much.
Of course, there's always the other possibility of wanting to snipe, but then again that would require them to post the chapter before LunaLotusScans, and all their work to snipe would've been for naught.
I thus do not believe that they had bad intentions for certain, even if they could've gone about it in a better way.
On a different note, I personally don't mind re-reading chapters with different translations.