I sort of accidentally opened a KiCad demo project:
and I was a bit flabbergasted by the PCB layout.
Although there is a lot of green on the bottom layer, it is all cut up by traces and it does not look much like a ground plane.
The 2 decoupling caps C6 and C7 are reasonable placed between the programming sockets, but U2 (74HC125) does not seem to have a decoupling cap at all.
But worse is (I think) the extreme unbalance in copper fill. This board is probably going to warp or even be rejected of that if you try to have it manufactured.
I can understand either a single layer board with a few straight wire bridges on the top layer or a dual layer board with a bit more attention given to details, but this triggers my CDO (Which is OCD spelled alfabetically as they should be!).
The board appears to be made by JP-Charras (Etched in Copper) which makes even weirder.