There doesn't seem to be new 7k mappers (unless I didn't notice). New players are likely to default to 4k if they haven't played beatmania or another rhythm game with 7k beforehand, hence there being more of them. Taking a look, it seems that past 7k mappers are taking time off. A list of them here, with ??? if not sure if they are contributing to the lack of 7k maps or not. This list is based on players that started beatmap projects or are QAT. I did not go through the BN list and may have missed several players, so this may not be accurate. Feel free to add to this:
inactive or partially inactive:
inactive or partially inactive:
asd123iii
- Yuuto - ???
Remillion Cross ???
Simple_Star
ishimaru94
[AyanoTatemaya] ???
Lieselotte
richardfeder