Inline bot message in secret chat is delivered without inline markup

Checklist

• I am reporting an issue in existing functionality that does not work as intended
• I've searched for existing GitHub issues

Description

A message with inline button is shown correctly on sender side.
On receiver side the message looks like text without inline markup.

BTW, on Android - there is no button for both parties of secret chat.

Expected Behaviour

The same message content (including markup) for both parties of secret chat is expected.
If it's not possible (for some reason), there should be an error on sender side.

Actual Behaviour

Inline markup (for messages forwarded from another chat / created via inline bot) is not shown for receiving party of secret chat.

Steps to Reproduce

1. Start secret chat
2. Use some inline bot to send message with inline keyboard markup (for example a URL-button)

Screenshots and Videos

Sending a button in secret chat:

From receiver perspective:

Environment

Sender Device: iPhone Xs
Receiver Device: iPhone 8

Sender iOS version: 13.3.1
Receiver iOS version: 13.3.1

Sender app version: 5.15.2
Receiver app version: 5.15.2

No source files, tests, or entry points are named. Start by reproducing the inline-bot message with an inline keyboard in an iOS secret chat, then trace secret-chat message handling; done means the receiver sees the same inline markup or the sender receives an error when it cannot be supported.