When the player creates a world in the standard "creative" game mode and enters the world in the rest it happens! However, if the player edits the default game mode for "Survival" and takes away, he edits the status from operator to member and press twice quickly the player will fly in survival mode as he had in the creative.
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We're tracking this issue in MCPE-67688, so this ticket is being resolved and linked as a duplicate.
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