Cant get limited file types upload to work

1

I have this.

title: BTS

accept:
  extension: webp

tabs:
  hero:
    label: Hero section
    icon: image
    columns:
      main:
        width: 2/3
        sections:
          hero:
            type: fields
            fields:
              blocks:
                type: blocks
                fieldsets:
                  - type: sectiontype1
                    name: sectiontype1
                    fields:
                      image1:
                        type: files
                      image2:
                        type: files
                      image3:
                        type: files
                  - type: sectiontype2
                    name: sectiontype2
                    fields:
                      image1:
                        type: files
                      image2:
                        type: files
                      image3:
                        type: files
                      image4:
                        type: files
                      image5:
                        type: files
                  - type: sectiontype3
                    name: sectiontype3
                    fields:
                      image1:
                        type: files
                      image2:
                        type: files
                      image3:
                        type: files

      sidebar:
        width: 1/3
        sections:
          files:
            type: files
            label: Files

But when I upload images I can still upload a png or jpg.
I want type files uploads to be limited to webp only.

What am I doing wrong here?

2

To restrict file uploads, you need a file blueprint with the accept setting. This does not belong in the page blueprint: File blueprint | Kirby CMS

Then you need to assign this file blueprint to your files fields: Files | Kirby CMS

On a side note, you use multiple files fields per block. But I think that only makes sense if you limit each field to allow only one file? Otherwise, you might as well use a single field only, that allows selecting multiple files.