People new to PCB design often make similar mistakes by lack of knowledge of PCB design in general, and limited knowledge of KiCad itself.
Sometimes I’m in a mood to do a review and even edit boards uploaded to this forum.
You may find it enlightening to read through them.
Two of those examples are:
https://forum.kicad.info/t/seek-review-my-first-design/15510
https://forum.kicad.info/t/please-check-my-first-pcb-design-in-kicad/15409
There are also tutorials about good pracices about PCB design on the 'net, and expensive and extensive books about EMC, “design for manufacturability” and other related topics.