I remember how absolutely jaw dropping FF8's cutscenes were at the time. I had never heard of Final Fantasy, saw some stills in magazines and thought "God damn, this game looks incredible!" Then I saw my friend actually playing it and as soon as the first cutscene ended it was like "Oh... OK. This is fine I guess."
On a similar vein, Arkham Knight (and in some cases Arkham City) looked worse in cutscenes if you maxed out the graphics settings. Obviously not if you ran it on a potato, but the games are somewhat well optimized these days*.
*At launch, Arkham Knight was an unoptimized, buggy mess. It has since gotten much better.
The cutscenes were rendered using certain graphics settings that you could exceed if you maxed out your own settings. Plus, because it was a pre-rendered video, there must have been some compression or something, as you could just tell when you're in a cutscene-- it was grainier and there was a smidge of artifacting. Don't quote me on this, but I believe the cutscenes were rendered at, like, 1080p, and if you were playing at 4K it would be a very noticeable downgrade. (Note that I did not and still do not have a 4K monitor)
Although thinking about it again, I do vividly remember some in-game-engine cutscenes in Arkham Knight. I'll have to replay that game again sometime to jog my memory.
Also, here’s the original source of the image if anybody for some whatever reason ever need it. It’s hard to crawl back for the source link since the original is really old at this point of time
Seen a teeny tiny bit of the hand drawn beginning cutscenes and it looks gorgeous, only to immediately discover later that the entire game was played in 16-bit 2D pixel
Yakuza, older games especially. You have amazing looking fully motion captured cutscenes which sometimes makes you forget that it's a video game due to how realistic it looks, but then you're out of the cutscene and the difference hits like a truck.
Dramatic zoom in on Kazuma Kiryu's painstakingly rendered pores. "I guess we're all the same deep down after all..." Looks up, sidequest jingle plays. Two seconds later, a ps2 man appears shouting "I'll kill you!" for a random encounter.
This is how I feel watching new CG trailers for each Elder Scrolls Online expansion. I already wanted to like it because I like the Lore and still enjoy watching the trailers because they look so cool, but I almost always say to myself "if only the game didn't suck so absolutely."