Miley Cyrus has that newly engaged glow ... flashing her shiny new ring while gushing about leveling up with Maxx Morando .

The singer appeared on "Good Morning America" Wednesday morning and spilled the tea -- saying she’s usually a total control freak, but she finally surrendered in her relationship with Maxx ... which is why that proposal completely blindsided her. Getty

Miley said everything in her life lined up perfectly -- from dropping her original song "Dream as One" for the upcoming "Avatar: Fire and Ash" ... to locking in her real-life love with Maxx -- and she couldn’t be more grateful for the double win.

She said she’s also done a ton of growing over their 4 years together -- and dropped a little wisdom too ... saying you always want someone by your side who hypes y

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