2.6.10
https://jsfiddle.net/618c7pe5/
Start USA English 64-bit Firefox 66.0.3 on USA English Windows 10. Visit https://jsfiddle.net/618c7pe5/ and then enter 1 to "km" field (it is the first number field).
The mil (second number field) should not have been red in Firefox. It should have accepted "0.621371" or "0,621371" as valid input.
In Firefox the "mil" (second number field) becomes red. It says "Please select a valid value. The two nearest valid values are 0 and 1". It doesn't like "0,621371".
Google Chrome and Firefox are USA English. Their preferred first language is USA English. Windows 10 is USA English. The HTML code in https://jsfiddle.net/618c7pe5/ indicates that the page is Turkish. I am located in Turkey. I think my location settings are "like in USA" because in Calculator 10 decimal numbers are like "3.1415".
Hey, as I said, this is not related to Vue. Also you still didn't provide a repro
It has been solved with step="any" https://stackoverflow.com/questions/36031499/firefox-does-not-allow-decimals-in-inputtype-number#comment94061330_36031715
Most helpful comment
It has been solved with
step="any"https://stackoverflow.com/questions/36031499/firefox-does-not-allow-decimals-in-inputtype-number#comment94061330_36031715