What kind of feature are you missing? Where do you notice a shortcoming of PTB?

When a user passes their list to Inline/ReplyKeyboardMarkup, we currently check if their input is valid (exactly 2 dimensional input is valid), i.e.

• the input is a sequence, not just a single button
• it's not just a simple sequence (sequence of buttons)

However it doesn't check if it's more than 2D, i.e. [[[KeyboardButton(...)], [...], ]] is invalid.

Describe the solution you'd like

Modify tg._utils.markup.check_keyboard_type to return False if we find another sequence.

Describe alternatives you've considered

No response

Additional context

No response