K7JBQ: Very simple, you have no scoring history, thus you're at the default rating of 150.
Practice rounds, or three holers on mobile, do not count toward an average.
You nailed it for me! Add "rooms" play and whatever gimmicks are available on mobile, they are deemed practice rounds and do not contribute to any stats,
including average.
Tier changes come by level, thus he is a Master.
This is not a pun - it's perfectly "normal" and legal for mobile players.
An average is obtained by playing ranked or tournament strokeplay (9 or 18 holes) which appear in the score history and contribute to the stats. The "150" should not be counted - it's but a placeholder AFAIK. Thus, the first score will be the first average.