In 36ad4817 (from March 2024) the HiddenFiles list changed from case-insensitive to case-sensitive, which doesn't make a lot of sense. Mist have misread the parameter which is 'CaseSensitive' instead of the usual 'IgnoreCase'. Additionally UseLocale should have been set False to keep the ordinal comparison.

Projects/Src/IDE.MainForm.pas

@@ -1052,7 +1052,8 @@ begin
   for Memo in FMemos do
     if Memo is TIDEScintFileEdit then
       FFileMemos.Add(TIDEScintFileEdit(Memo));
-  FHiddenFiles := TStringList.Create(dupError, True, True);
+  FHiddenFiles := TStringList.Create(dupError, True, False);
+  FHiddenFiles.UseLocale := False;
   FActiveMemo := FMainMemo;
   FActiveMemo.Visible := True;
   ActiveControl := FActiveMemo;