diff --git a/discord/ext/commands/converter.py b/discord/ext/commands/converter.py
index 4ea649490..9c398a389 100644
--- a/discord/ext/commands/converter.py
+++ b/discord/ext/commands/converter.py
@@ -982,7 +982,7 @@ class clean_content(Converter[str]):
 
             def resolve_member(id: int) -> str:
                 m = _utils_get(msg.mentions, id=id) or ctx.bot.get_user(id)
-                return f'@{m.name}' if m else '@deleted-user'
+                return f'@{m.display_name}' if m else '@deleted-user'
 
             def resolve_role(id: int) -> str:
                 return '@deleted-role'
@@ -990,7 +990,7 @@ class clean_content(Converter[str]):
         if self.fix_channel_mentions and ctx.guild:
 
             def resolve_channel(id: int) -> str:
-                c = ctx.guild.get_channel(id)  # type: ignore
+                c = ctx.guild._resolve_channel(id)  # type: ignore
                 return f'#{c.name}' if c else '#deleted-channel'
 
         else:
diff --git a/discord/message.py b/discord/message.py
index ee6935b00..0bc9b6296 100644
--- a/discord/message.py
+++ b/discord/message.py
@@ -592,9 +592,9 @@ class Message(Hashable):
 
             The order of the mentions list is not in any particular order so you should
             not rely on it. This is a Discord limitation, not one with the library.
-    channel_mentions: List[:class:`abc.GuildChannel`]
-        A list of :class:`abc.GuildChannel` that were mentioned. If the message is in a private message
-        then the list is always empty.
+    channel_mentions: List[Union[:class:`abc.GuildChannel`, :class:`Thread`]]
+        A list of :class:`abc.GuildChannel` or :class:`Thread` that were mentioned. If the message is
+        in a private message then the list is always empty.
     role_mentions: List[:class:`Role`]
         A list of :class:`Role` that were mentioned. If the message is in a private message
         then the list is always empty.
@@ -947,10 +947,10 @@ class Message(Hashable):
         return [int(x) for x in re.findall(r'<@&([0-9]{15,20})>', self.content)]
 
     @utils.cached_slot_property('_cs_channel_mentions')
-    def channel_mentions(self) -> List[GuildChannel]:
+    def channel_mentions(self) -> List[Union[GuildChannel, Thread]]:
         if self.guild is None:
             return []
-        it = filter(None, map(self.guild.get_channel, self.raw_channel_mentions))
+        it = filter(None, map(self.guild._resolve_channel, self.raw_channel_mentions))
         return utils._unique(it)
 
     @utils.cached_slot_property('_cs_clean_content')
@@ -970,40 +970,47 @@ class Message(Hashable):
             respectively, along with this function.
         """
 
-        # fmt: off
-        transformations = {
-            re.escape(f'<#{channel.id}>'): '#' + channel.name
-            for channel in self.channel_mentions
-        }
+        if self.guild:
 
-        mention_transforms = {
-            re.escape(f'<@{member.id}>'): '@' + member.display_name
-            for member in self.mentions
-        }
+            def resolve_member(id: int) -> str:
+                m = self.guild.get_member(id) or utils.get(self.mentions, id=id)
+                return f'@{m.display_name}' if m else '@deleted-user'
 
-        # add the <@!user_id> cases as well..
-        second_mention_transforms = {
-            re.escape(f'<@!{member.id}>'): '@' + member.display_name
-            for member in self.mentions
-        }
+            def resolve_role(id: int) -> str:
+                r = self.guild.get_role(id) or utils.get(self.role_mentions, id=id)
+                return f'@{r.name}' if r else '@deleted-role'
 
-        transformations.update(mention_transforms)
-        transformations.update(second_mention_transforms)
+            def resolve_channel(id: int) -> str:
+                c = self.guild._resolve_channel(id)
+                return f'#{c.name}' if c else '#deleted-channel'
 
-        if self.guild is not None:
-            role_transforms = {
-                re.escape(f'<@&{role.id}>'): '@' + role.name
-                for role in self.role_mentions
-            }
-            transformations.update(role_transforms)
+        else:
+
+            def resolve_member(id: int) -> str:
+                m = utils.get(self.mentions, id=id)
+                return f'@{m.display_name}' if m else '@deleted-user'
+
+            def resolve_role(id: int) -> str:
+                return '@deleted-role'
+
+            def resolve_channel(id: int) -> str:
+                return f'#deleted-channel'
+
+        transforms = {
+            '@': resolve_member,
+            '@!': resolve_member,
+            '#': resolve_channel,
+            '@&': resolve_role,
+        }
 
-        # fmt: on
+        def repl(match: re.Match) -> str:
+            type = match[1]
+            id = int(match[2])
+            transformed = transforms[type](id)
+            return transformed
 
-        def repl(obj):
-            return transformations.get(re.escape(obj.group(0)), '')
+        result = re.sub(r'<(@[!&]?|#)([0-9]{15,20})>', repl, self.content)
 
-        pattern = re.compile('|'.join(transformations.keys()))
-        result = pattern.sub(repl, self.content)
         return escape_mentions(result)
 
     @property