diff --git a/aiogram/dispatcher/filters/builtin.py b/aiogram/dispatcher/filters/builtin.py
index 484dd973..b80448c9 100644
--- a/aiogram/dispatcher/filters/builtin.py
+++ b/aiogram/dispatcher/filters/builtin.py
@@ -180,7 +180,7 @@ class CommandStart(Command):
                 return {'deep_link': match}
             return False
 
-        return False
+        return check
 
 
 class CommandHelp(Command):
diff --git a/aiogram/utils/callback_data.py b/aiogram/utils/callback_data.py
index b0162a7e..e24ad7b1 100644
--- a/aiogram/utils/callback_data.py
+++ b/aiogram/utils/callback_data.py
@@ -75,7 +75,7 @@ class CallbackData:
             raise TypeError('Too many arguments were passed!')
 
         callback_data = self.sep.join(data)
-        if len(callback_data) > 64:
+        if len(callback_data.encode()) > 64:
             raise ValueError('Resulted callback data is too long!')
 
         return callback_data
diff --git a/aiogram/utils/deprecated.py b/aiogram/utils/deprecated.py
index 5232e8a3..83a9034c 100644
--- a/aiogram/utils/deprecated.py
+++ b/aiogram/utils/deprecated.py
@@ -102,14 +102,18 @@ def renamed_argument(old_name: str, new_name: str, until_version: str, stackleve
         is_coroutine = asyncio.iscoroutinefunction(func)
 
         def _handling(kwargs):
+            """
+            Returns updated version of kwargs.
+            """
             routine_type = 'coroutine' if is_coroutine else 'function'
             if old_name in kwargs:
                 warn_deprecated(f"In {routine_type} '{func.__name__}' argument '{old_name}' "
                                 f"is renamed to '{new_name}' "
                                 f"and will be removed in aiogram {until_version}",
                                 stacklevel=stacklevel)
+                kwargs = kwargs.copy()
                 kwargs.update({new_name: kwargs.pop(old_name)})
-                return kwargs
+            return kwargs
 
         if is_coroutine:
             @functools.wraps(func)
diff --git a/tests/test_filters.py b/tests/test_filters.py
index 0592f31b..f29e1982 100644
--- a/tests/test_filters.py
+++ b/tests/test_filters.py
@@ -276,7 +276,7 @@ class TestCommandStart:
         test_filter = CommandStart()  # empty filter
         message = Message(text=self.START)
         result = await test_filter.check(message)
-        assert result == {'deep_link': None}
+        assert result
 
     async def test_start_command_payload_is_matched(self):
         test_filter = CommandStart(deep_link=self.GOOD)