Resizing Photo don't work anymore

I am not getting it. Can you describe steps you are taking that does not work to resample (resize) image?

The resizing itself looks perfectly fine here, the pixel size is correct.

However, there appears to be a display scaling issue here - if these screenshots are both 100% or at least the same scale. It would help if you could provide full-screen screenshots with the original image in Photoshop together with each dialog.

Is this a retina display? In that case the image will natively be smaller on screen than on a traditional display. Photoshop should always display one image pixel represented by exctly one physical screen pixel - in other words "small". All dialogs should do this too.

All other consumer-oriented apps, including the native MacOS apps, will scale images up to 2x linear dimensions when a retina/4K display is detected. This is the industry-standard workaround to ensure the same material can be used regardless of screen technology.

Legacy Save for Web is obsolete.

Use File > Export > Export As.  Adjust image size (width & height in pixels) as needed.

So I think you enter the new size in Pixels in the B or H form by clicking inside it and entering the desired Pixels, and both B/H and the "Afmetingen" should also relect the new value. Then after clicking OK, the Image Size box will vanish and your image should change to the new dimensions.

If this is not working, Exit Photoshop and go to Security and Privacy and see that Photoshop has Full Disk Access. Then restart your Mac and see if that does fix it.