Question huuuge build size of my small tool

unity version 2021.3.4f1
windows

I build ,target windows , compression method is Default.
The build report is below
Build Report
Uncompressed usage by category (Percentages based on user generated assets only):
Textures 1.6 mb 28.7%
Meshes 0.0 kb 0.0%
Animations 0.0 kb 0.0%
Sounds 89.7 kb 1.6%
Shaders 29.4 kb 0.5%
Other Assets 3.7 mb 65.7%
Levels 0.0 kb 0.0%
Scripts 158.0 kb 2.8%
Included DLLs 0.0 kb 0.0%
File headers 44.5 kb 0.8%
Total User Assets 5.6 mb 100.0%
Complete build size 72.4 mb

What happened to my project?What is the difference between 5.6mb and 72.5mb?
How to reduce Complete build size?
I tried to change compression method ,but the difference is only 10mb...

 

Unity also has it's own code to make the game run. Maybe increase code striping level and for some platforms enable engine striping. Also remove any packages you dont use. And make sure only 1 graphics API is used to avoid multiple shaders. Striping quality settings when possible also could help

 

Thanks for reply.
I tried and got about 50MB output.
However unity should reduce output size.
if I make same app by other tool,the app size will be more and more small.