Things we should drop in v14. The list is probably not complete. This includes everything deprecated in v12.x and v13.x.

• DRop support for py3.6 - reaches EOL in december anyway … Remove __dict__ from __slots__ #2619 & Update python version in Readme and setup.py #2636

• Don't know why we skipped that in Use @abstractmethod instead of rasing NotImplementedError #1905, but as BasePersistence is an interface, it makes sense for all methods to be abcs. As flush currently doesn't raise NotImplementedError, this is strictly speaking breaking, so putting this on the v14 milestone. Make basepersistence methods abstractmethod #2624
• non-context based callbacks (i.e. all the pass_* arguments) Dropping non context #2617
• allow_edited argument of CommandHandler Dropping non context #2617
• non-filter arguments of MessageHandler Dropping non context #2617
• RegexHandler Dropping non context #2617
• bot argument of JobQueue Doc fixes #2597
• use_context argument of Dispatcher and Updater (this is discussable. we could keep that until v15 as convenience for everyone who already switched to context based callbacks - then again, for adjusting your code to v14, this will be the easiest part …) Dropping non context #2617
• MessageQueue & DelayQueue as a whole (we might want to add some of the logic back in Refactor MessageQueue #2139 after the asyncio switch, but maybe it's cleaner to just remove everything in case Refactor MessageQueue #2139 will make it only to v14.1 or so) Remove deprecated things #2644
• drop __dict__ from __slots__ (users won't be able to set custom attributes on PTB objects) Remove __dict__ from __slots__ #2619
• make BP.refresh_*_data abstract methods Make basepersistence methods abstractmethod #2624
• make Persistence.store_callback_data default to True and make BP.get/update_callback_data abstract methods. Make basepersistence methods abstractmethod #2624
• Move TelegramDecryptionError to error.py (851f0b7, it was reverted since it was breaking) move telegramdecryptionerror to error.py #2621

Originally from #2347:

• The @run_async decorator Remove deprecated things #2644
• Filters.{private, group} Remove deprecated things #2644
• utils.{promise, webhookhandler} Remove deprecated things #2644
• clean argument of Updater.start_{polling, webhook} Remove deprecated things #2644
• Think about removing Defaults from tg.Bot completey and moving them to tg.ext.ExtBot. We may have to think about how to handle signatures with DefaultVaule, then, i.e. if _insert_defaults should stay in tg.Bot or should be moved to tg.ext.ExtBot. Move defaults to ext #2648

• Args & attributes of ChatMember Fix method signatures and expand test_official #2643
• Bot.{kick_chat_member, get_chat_members_count} Remove deprecated things #2644
• Chat.{kick_member, get_members_count} Remove deprecated things #2644
• ChatAction.{RECORD, UPLOAD}_AUDIO ? Remove deprecated things #2644