In the new stable Telegram for Android v12.

In the new stable Telegram for Android v12.10.5 (7105), a new «Show experimental settings» option has been added to the debug menu. It opens a new «Round Video» menu. This menu is designed to configure the recording quality of round video messages.

Previously mentioned:
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*To open the debug menu, go to Settings and tap the version number twice.

@telelakel