Worse comes to worse, role back your files via a windows file backup

There was no update today for either Arma Reforger, Arma Reforger Exp, or their tool sets. The main was last updated in early Sept., and the exp build was last updated in late Sept. I dont know what you were doing at the time, whether it was importing a mesh, generating a terrain, or mucking about in the files, but whatever you did, it appears to have caused a memory leak. Either that, or your RAM is giving out

Okay, I' not saying this to be mean but to provide context. Arma Reforger is an extremly optimized game from the mesh vert-/tri count, LOD transitions, and VRAM usage (maybe some script optimization is needed here and there, but thats not going to bring about getting the Xbox S anywhere near a stable 60 FPS. Im sure you've heard it before, but your running a budget setup on a very demanding game. Just to put it into perspective, you as an Xbox S user are already forced to use lower resolution textures relative to other platforms to reduce your VRAM usage; all textures for you load in using their level 2 mipmap rather than level 0. Your render distance is locked to btw/ 400-800 meters depending on your graphic setting to vastly limit just how many props are loaded in. I know what your asking for is a reasonable ask from the perspective of someone who paid for $40 for a game (ie, you'd like a functional product), but the ask from a developers perspective given the context is impossible. They're never gonna tell you that bc as an employee, they cant. However, at the end of the day, the only thing you can do to get better FPS is to change your hardware b/c there is very little that can be done at this point in the game's development to boost your FPS beyond what your currently getting.

Im sure this comment will be deleted by the mod but this is the hard truth.

I'm just gonna chime in here on two potential causes:
1) Deadzone in your desk (unrelated to Reforger, but would explain the issue persisting for two mice if wireless)

2) BattleEye conflict w/ mouse driver (related to Reforger, but would only explain the issue persisting for two mice if they are of the same brand. I had a somewhat similar issue w/ my Netgear wifi adapter causing the blue screen of death whenever I booted up Reforger. Best to completely delete and reinstall your device driver)

This is not a bug, but rather a result of how the level of detail (LOD) transition system for models is deisgned for most, if not all, games. LODs are an optimization technique in video games that reduces the complexity of 3D models and textures as they get further from the player. In Arma Reforger, the distance between when an LOD transitions from one LOD to the next LOD (eg, LOD0 -> LOD1, LOD1 -> LOD2, ..., LODX -> Derendered) depends on a model's volume. As you can see in the attached image, the BTR-70 and the M923A1 trucks have a greater volume than LAV-25 and Ural-4320 trucks, respectively.

Point is, its not a bug or accident. The system is designed to do this for all models as a way of optimally managing vertex/triangle count to improve the game's FPS. Bigger models require greater distance between the player's camera and the model to derender compared to smaller models.