Honestly, the question of what problems is solves is a good one and of course, user dependent. However, I think just problem solving is too simplistic. Often a new feature doesn't solve what you might consider a "problem" but instead adds a benefit that facilitates getting keepers on the card in ways that didn't exist before.
At any rate, here are the features I think will make a difference for me in the field...
High frame rate + good buffer + High res. Until recently with the Canon R5, this hasn't been an option and something I have certainly wanted for my action work. To put up to 30 high-res frames per second down on a rapidly flying bird is a game changer.
Speaking of the frame rate, I know a lot of people have been beating up the camera for it's 30FPS in lossy 12 bit only, but keep in mind that full 14 bit lossless at 20FPS ain't too bad! Up till a few days ago, no consumer camera could give you 30FPS. Plus, it seems like getting to the highest frame rate in any mirrorless cameras involves compromises of some sort. For me, 20FPS @50MP is more than adequate.
Faster readout - this one is overlooked quite a bit, but it's estimated this camera can read the sensor at 1/240th of a second. This virtually eliminates the possibility of rolling shutter, so you can do high-speed action in complete silence and not worry about weird-looking warped wings / legs.
No blackout - I realize the a9 series has this feature, but it really is game-changing for tracking. The faster readout and EVF on the a1 means that this blackout free experience is also likely to be completely lag free.
1/400th flash sync. This is incredibly valuable for fill flash with wildlife. 1/250th is sometimes too slow, especially hand-holding longer glass. High speed flash sync can work around this a bit, but it uses far more power and greatly reduces distance. 1/400th gives more speed without distance compromise.
Bird eye AF - if this works well for flight shots, it's a game-changer. Imagine being able to completely focus on the composition as the bird is flying without worrying about where the AF area is. No more sharp wingtips because you allowed the AF area to get too close to the wings. So often, there is so much going on with a flight sequence that composition tends to take a back seat - this alone is worth the upgrade (again, if it works as advertised).
AF accuracy - The a1 also performs twice as many AF calculations per second as the a9ii - which is already very impressive. This should directly translate into more AF accurate tracking.
There's probably a few others I'm forgetting, but those are the reasons / problems it solves (or makes easier) for me.
