Misleading error message when required fields are missing

[connium]

Describe the bug
When applying for an Ehrenamtskarte and I click on the button "Antrag abschicken" without having filled all required inputs on page 3, the message "Ungültige bzw. fehlende Eingaben entdeckt. Bitte prüfen Sie die rot markierten Felder." is shown, but there aren't any inputs marked red.

To Reproduce
Steps to reproduce the behavior:

1. Apply for an Ehrenamtskarte. Enter valid data for page 1 and 2.
2. On page 3 enter only some data and leave at least one required input field empty.
3. Scroll down and click on step 4.
4. Tick the necessary checkboxes.
5. Click on "Antrag abschicken".
6. See the error message. The indicator for step 3 shows a checkmark, which indicates, that everything is correct. Even if I reopen the page for step 3, nothing is marked red.

Expected behavior
If the message tells me there are red marked fields, there should be some.

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: Fedora
• Browser Firefox 134

Smartphone (please complete the following information):

• Device: LG Q7
• OS: Android 9
• Browser stock browser (Chrome)

Additional context
IMO there are multiple solutions we could consider:

1. Mark all fields red, when clicking the "Nächster Schritt" button.
2. Think of a different error indicator at least for Android, because the tooltip vanishes immediately when the corresponding field receives the focus.
3. Think of a proper error indicator for the drop down "Einsatzgebiet" because on Android it was not obvious to me, that this field was missing.
4. Do not mark step 3 with a check mark, if there are still errors in the form.
5. Rephrase the error message to refer to "required inputs" instead of "red marked inputs".
6. ...