Animes that are perceived as sad by majority of the community but not you.

Kotonoha no Niwa is what immediately comes to my mind lol. I still don't get what was so sad about that anime movie.

Grave of the Fireflies...I find it kinda on the nose with its subject matter, like it wants to teach me "war bad" by showing someone shoot a puppy. Like yeah, shooting puppies is bad and sad, but man are you so obvious with the emotional manipulation, the beautiful Ghibli animation and sad music while you shoot the puppy. And then the movie ends with a judgmental stare of the titular character, just to make sure that you get the "war bad" message one last time.

The difference is that War on the Pocket isn't telling of a real world events and specific suffering of a real world country and it's people though characters that could have existed. By that there are levels of disassociation, despite the general "war bad" motif of pretty much every Gundam piece of media, and how tragic all of it can get, that is not Build series. The Mecha and the entire industry around their marketability really do kinda ruin the messaging of Gundam (insert the meme of Gundam shooting and the human missing the point of the story just to look at cool robots).

Also, it didn't go and shoot a puppy like grave of the fireflies did, linger on how shooting the puppy is so sad, with all the sad music and repeated shots of the puppy when it was happy and alive, and then have the main character literally look at the camera, breaking the 4th wall, in an obvious judgemental look to finish the movie. War in the Pocket is more subtile that that at least, despite it being part of a heavily merchandise franchise. Plus it doesn't try to make you cry for all the sad feels, I don't think I've heard anyone cry over the ending of War in the Pockets, at most they were depressed "man" or "that's rough" kinda looks and reactions.

AnoHana seconded, predictable, boring etc. I think the drama is rather poorly contrived.
If not for the OST, Tenki No Ko is not that sad imo
I love frieren, but it is not as sad as others say, it’s more relaxing/ thought provoking/ wholesome than anything

After doing a quick search I found out that Angel Beats is considered as sad by many, but I don't remember shedding a single tear of sadness.
Instead it made me laugh quite hard a few times, so I'm surprised that it doesn't have the comedy tag here.