Tip for better immersion
Perspective of the character I am reading: this is one of the most common mistakes I see for a fist perspective story. It usually isn't an issue for transmigration novels (unless it's from a non-transmigration character in the story) because those characters are supposed to have the same supposed preconception as we have. Like what we consider a monster and an animal, religious beliefs, magic etc.
The problem for me stems from the fact when a character that was born in that world starts talking as if he/she/it is from our modern world.
example: Tiffany, side character, grew up in a merchant family, it was decided for her to become a nun for a god of healing and one of the more powerful gods in the settings pantheon so she can become a healer, bring more wealth to her family and the blessings of a powerful god. What my experience so far has been for most authors is that they will make the character skeptical of the cult and indoctrination for the religion because she was born of a merchant family and they think she will be more skeptical of the belief.
I think most authors will miss one important thing in this example... which is culture. What is the culture of the country, city, family she comes from? Is she from a country which has a pope leader with the majority of power? Has she lived a difficult life to where she doubts everyone and everything? There are thousands of factors that could be used to explain why her behavior might deviate from the norm of the setting. But not all characters need to deviate from the norm to the point of it being immersion breaking.
Here is another example: Nazi Germany. Let's say we have 10000 people growing up from a small age in Nazi Germany. Out of those 10000 people, in adulthood over 9000 would become Nazis, while the others would not be per say Nazis it doesn't mean they won't act like it because it's the norm. Because people are very impressionable and a dictatorial-ism can go a long way. This was an extreme example but I think it got my point across.
So if Tiffany grew up in a very Religious setting and set out to become a nun, statistically she would be very a pious person. So then when Tiffany meets our main character of this example story, who is a transmigrator. Why, when he asks about magic/religion/animals etc does she respond like it's a normal question? Like for us a goblin might be a monster, but for Tiffany it might be a pesky animal that is dangerous in larger numbers, like wolfs are. Why, when she talks about her religion she talks if it's not an important part of her life? Why, when she talks about magic, she makes it sound like magic and physics are 2 different things, which also coincide with the MCs views of the world?
This is essentially my most common immersion breaker for fantasy settings. Magic should not be separated from their reality, it should be their reality. Monsters should essentially be monstrous creatures and not some common stuff like goblins, dire wolfs, orcs, ogres. Like you can imagine Ogres as Lions and Goblins as Hyenas for Africa, if you properly equipped you can deal with them, but if not.... let's just leave this part out. Religion most of the time has more variation between stories so I'll leave this part out.
This is advice, not some law that you need to obey. If you are an author that is guilty of this crime, take this as criticism to improve in the future (or don't) and not an attack on your person pls. That is all and please be civil in the comment section.
P.S No offence with the Nazi example.
Again, thank you for the post, and I hope more writers will heed your advice.