Screen.SetResolution not behaving as expected

Hey, I've been having an issue that has been making me feel insane for a couple of days now. I've looked everywhere but nothing seems to work.

Whenever I use Screen.SetResolution(), the aspect ratio doesn't change correctly. When I start the game, the highest resolution my monitor supports is applied and looks correct. But, whenever I change my resolution, the aspect ratio (no matter what resolution I choose) gets set to something like 4:3 or 5:4. Obviously, I want the aspect ratio to reflect what the resolution's aspect ratio is. I've attached scripts from my resolution dropdown and my display manager (a script so I can change resolution, fullscreen, etc. from anywhere) and screenshots of my player settings and what the window looks like after I change the resolution.

Resolution Dropdown:

     Resolution[] resolutions;
     Dropdown resolutionDropdown;
 
     public void Start()
     {
         resolutionDropdown = GetComponent<Dropdown>();
         resolutions = Screen.resolutions;
         resolutionDropdown.ClearOptions();
         List<string> options = new List<string>();
 
         int currentResolutionIndex = 0;
         for (int i = 0; i < resolutions.Length; i++)
         {
             //I didn't want multiple of the same resolution just with different refresh rates appearing, so I added this check to make sure there aren't duplicates.
             if (i > 0 && resolutions[i].width == resolutions[i - 1].width && resolutions[i].height == resolutions[i - 1].height) { }
             else
             {
                 string option = resolutions[i].width + " x " + resolutions[i].height;
                 options.Add(option);
                 if (resolutions[i].width == Screen.width && resolutions[i].height == Screen.height) currentResolutionIndex = i;
             }
         }
         resolutionDropdown.AddOptions(options);
         resolutionDropdown.value = currentResolutionIndex;
         resolutionDropdown.RefreshShownValue();
     }
 
     //This is called when a player selects a resolution from the dropdown
     public void SetResolution(int resolutionIndex)
     {
         //Since I change the value in Start (when showing all the options), I need to add this check so it doesn't automatically change. 
         //If you have another way of doing this that is better, please let me know.
         if (Time.timeSinceLevelLoad > 0.1f)
         {
             Resolution resolution = resolutions[resolutionIndex];
 
             PlayerPrefs.SetInt("resolutionX", resolution.width);
             PlayerPrefs.SetInt("resolutionY", resolution.height);
             PlayerPrefs.Save();
 
             DisplayManager.instance.AdjustResolution();
         }
     }

DisplayManger:

 public static DisplayManager instance;

 void Start()
 {
     instance = this;
 }

 public void AdjustResolution()
 {
     bool fullscreen = false;

     if (PlayerPrefs.GetInt("fullscreen") == 1) fullscreen = true;
     else fullscreen = false;

     Screen.SetResolution(PlayerPrefs.GetInt("resolutionX"), PlayerPrefs.GetInt("resolutionY"), fullscreen);

     //This prints out the correct resolution that I just selected.
     Debug.Log("Resolution: " + PlayerPrefs.GetInt("resolutionX") + " x " + PlayerPrefs.GetInt("resolutionY") + ". Fullscreen: " + fullscreen);
 }

Player settings. I've tried changing the fullscreen mode but that doesn't seem to work either.

Then here is what the game looks like when I am running it. It is supposed to be 1920 x 1080. I should mention that my monitor is 3440 x 1440, but even selecting 3440 x 1440 produces a similar result.

Any ideas about what may be causing this and how I could fix it?