Recently, I decided to rewatch this anime. However, I've found that some scenes are different from what I remember or missing. For example, when Milim first arrived, after Rimuru subdued her with honey, there was supposed to be a scene of the two riding on Ranga as they traveled towards town. But from what I just watched there was only a scene where they chat in the forest and then it jumps to Milim punching Gabiru. Or after the Carrion's subordinate and Charybdis thing, after Rimuru takes out the thing possessing Carrion's subordinate, they were supposed to be located on some kind of concrete flooring/rubble. And Milim lies down on the rubble, then as she sits back up she has an epiphany that Clayman is up to something. But in the anime, it's in the forest at sunset. In short, the anime is different from what I remembered from when I first watched it. Is it that the anime has been edited/cut after publishing or am I just confusing the manga and anime?
Changes are oft times made when making a manga from a novel or an anime from a manga, and even if the anime strictly adheres to the manga's plot, you will still inevitably notice changes. For instance, Tokyo Ghoul season 2 anime is completely different from its manga, the ending part of Erased anime is dramatically different from its manga... To summarise, there are always bound to be some differences between the manga and anime. These changes may even be made to make the story more interesting (or in case of Tokyo Ghoul, to destroy it) and to cover the gap between the two different mediums, i.e., manga and anime.
It's not really new for most parts of a light novel especially to be ommited esp if the animation studio just decided to test the parts of because they deemed the extra info as unnecessary and also for readers who are really interested in the story to just read the ln. At the first place Lns turning into an anime is honestly usually just for all the hype so they would be able to sell the anime well cause prev fans are already there = less profit risk and as long as they make the Charas look pretty decent shits usually just all good.
Btw, I'm pretty sure you may be confusing the manga and anime, coz I've read the manga and seen the anime as well.