It is not an unusual thing to see a bug happen in PUBG Mobile. The developer needs to keep the game lightweight for better performance and as a result, bugs happen. Some can cause you a funny death while some can give you advantages that other players don't have. If you abuse a bug in PUBG Mobile, you will get banned according to the official answer from PUBG Mobile support.
During a match in the PUBG Mobile Pro League Scrims on April 18, team Elementrix used a smoke bug in PUBG Mobile and killed MortaL so they were disqualified. If you don't know what the smoke bug is then let me explain. The Smoke bug is a way to exploit the perspective feature in PUBG Mobile by changing from TPP to FPP so the player can see through the smoke while other players cannot.
So, in the scrims, it was the final circle, MortaL was the only survivor of his team at the time. He threw multiple smoke grenades to push the tower of 2 Elementrix members. However, while he was staying in the smoke near the tower, somehow he still got shot down in less than a second by Ex.Ontop. When checking the POV of Ontop, it seems that he has changed from TPP to FPP to exploit the smoke bug and spot MortaL.
To explain the bug more clearly, MortaL has also demonstrated this bug on his stream in the Training Mode so people can understand better. Changing to FPP will make the smoke thinner, thus you can see through it while other players cannot.
In response to this matter, Ex.Ontop also clarified on his Instagram that he didn't intend to use the bug and it was just his habit to switch to FPP in close combat. But the decision has been already carried out so it doesn't really matter anymore. PUBG Mobile dev also has a part of responsibility in this matter since it's their job to keep the game bug free for the competitive scene.
Also check out: Fnatic Is Going To Pick Up Another PUBG Mobile Roster In India As Team Rise.