I just had a look at other threads about the Seestar, most of them have strechted stars at all or one corner.
To be honest, the Seestar is a nice piece to look into deep space, but for the price you can’t expect a picture quality like an equipment which is 3 times more expensive.
Those stars could be corrected in postprocessing.
Siril f.e. is free, but it takes a while until you get good results.
I use Pixinsight, but it’s not free.
No one of the good Astropics you can find around is simply stacked, they require “a little bit” more of work.
Don’t expect perfect pictures at the beginning with astrophotography, it’s a long way to go 😉