Production and development builds look different

I deployed my app to server and I realized it looks differently than before. The difference is in a way how it is compiled. The source code and configuration is the same.

Staging / production build

This is incorrect:

> vue-cli-service build --mode staging
-  Building for staging...
WARNING  Compiled with 2 warnings                                                                                                                                                                                                                  
asset size limit: The following asset(s) exceed the recommended size limit (244 KiB). This can impact web performance.
js/app.50688000.js (1.32 MiB)
js/content-chunk.2f6c3afb.js (457 KiB)
images/opravit.jpg (580 KiB)

entrypoint size limit: The following entrypoint(s) combined asset size exceeds the recommended limit (244 KiB). This can impact web performance.
app (1.32 MiB)
File                                Size                Gzipped
dist\js\app.50688000.js             1348.69 KiB        374.68 KiB
dist\js\content-chunk.2f6c3afb.js   456.97 KiB    134.96 KiB
dist\js\user-chunk.b63740d1.js      126.05 KiB    24.50 KiB
dist\js\admin-chunk.3b1a4900.js     109.80 KiB    27.37 KiB
dist\precache-manifest.4a0f46273bd546044576dff695d5e166.js    10.04 KiB  3.22 KiB
dist\service-worker.js              0.95 KiB      0.54 KiB

Development build

This is correct:

> vue-cli-service build --mode development
/  Building for development...
DONE  Compiled successfully in 15571ms                                                                                                                                                                                                            
File                        Size       Gzipped
dist\js\app.js              5993.07 KiB      1028.17 KiB
dist\js\content-chunk.js    1528.93 KiB      270.62 KiB
dist\js\user-chunk.js       492.50 KiB       43.81 KiB
dist\js\admin-chunk.js      167.63 KiB       11.08 KiB

Source code

Where is the issue? When I open Chrome tools I can see there is less style sheets in document header in the production build. How can I fix it? Thanks