Changing the border radius of the input field is currently not possible: WordPress/gutenberg#51617 (on a global level)

Should all text input elements, like in the log in or comments, have the same radius?

Should only the placeholder text be regular, or also the text that the user enters into the field on the front?

Should all text input elements, like in the log in or comments, have the same radius?

All text inputs should ideally have the same radius, yes.

Should only the placeholder text be regular, or also the text that the user enters into the field on the front?

The placeholder and the text users enter should both be Regular.

Ouch the form for the login/out block is especially bad. I did not know that this button is missing the CSS class that styles the buttons.

Found an issue for it: WordPress/gutenberg#50466

Can all input fields have the same border radius as the search?

I added a screenshot here: #398

Great, thank you!