Storybook javascript GET 404 (Not Found) error about components

I need to fix a Storybook with stories, it’s broken (it’s unclear when it was broken, probably after some angular upgrades a while ago), it didn’t work for some time.
Currently, some of stories are displayed properly, however for most of stories there are similar javascript errors. The stories with that js errors are not displayed at all.

It’s a huge Angular project.
For many stories the js errors are (or similar for another story, with another components):

Is it related to the angular code itself, or it’s all about .storybookmain.js ?

If this is helpful, then:

start-storybook -V
6.0.28

node -v
v14.18.1

ng --version    
@angular-devkit/architect          0.901.15
@angular-devkit/build-angular      0.901.15
@angular-devkit/build-ng-packagr   0.901.15
@angular-devkit/build-optimizer    0.901.15
@angular-devkit/build-webpack      0.901.15
@angular-devkit/core               9.1.15
@angular-devkit/schematics         9.1.15
@angular/cdk                       9.2.4
@angular/cli                       9.1.15
@angular/material                  9.2.4
@ngtools/webpack                   9.1.15
@nguniversal/common                9.1.1
@nguniversal/express-engine        9.1.1
@schematics/angular                9.1.15
@schematics/update                 0.901.15
ng-packagr                         9.1.5
rxjs                               6.6.7
typescript                         3.7.7
webpack                            4.42.0

Any ideas how to fix it? Thank you.

P.S. Upgrading/downgrading storybook didn’t help that much, so it was decided to stick with a current one Storybook of 6.0.28 (at least some of many stories are displayed).