I sure wish the LN readers wouldn't talk about the LN in a manga discussion. Seriously they are almost always in the comments saying things that can range from seemingly harmless to straight up spoilers that make the series unreadable.
Seriously, if its knowledge from the source material, don't mention it. Does not matter what it is, its a spoiler. Tone, pacing, names and "fun facts" or "clarifications" are all spoilers and should be placed under a spoiler tag at the least.
Saying the story "gets darker" is a spoiler. Saying a character "is useless" in the context of having read the source, is a spoiler. Also be careful responding to spoilers. If you respond to a hidden spoiler with positivity or negativity it can basically tell people what the spoiler was. If you support a ship or want the MC to get laid and someone spoilers you, don't respond with "Hurray, thanks" because we can put 2 and 2 together quite easily and now we have been spoiled. Knowing a spoiler makes you happy or sad is a spoiler because your comments will tell us what would make you happy or sad.
Sorry for the rant comment but it really bothers me how lax people are in these comment sections when it comes to talking about the LNs and future chapters and spoilers in general. I really want to chat with people and read comments for fun while leaving my 2 cents, but i can't do that when scrolling down means playing a Russian roulette of spoilers.
If it wasn't explained in THIS material, its a spoiler. That also includes spin off series and such which should be discussed in their own space or placed behind spoiler tags for those series. Sometimes people will read the main story before the spin off after all even if they release at the same time.