The HR interview went well and it was good and correct. Then they requested an example task to be developed without any libraries/framework except jquery. Yes, in 2020 you read it correctly.
It was the first red flag definitely for me but after what came after this was utter nonsense. Whoever checked the code was clearly in his head. They criticized the purpose of modularity (why not a single file) and not using any tools/libraries, which was requested in the first place.
In short, they questioned their own rules of the project and even the UI which is funny because they gave me that with written: "follow as strict as you can".
Don't work here. They couldn't even follow their own legacy rules and type the feedback correctly.