Unfortunately for login sites your going to have to contact their support to find out why this is happening. Firefox user forum can't access or diagnosis a login site issue here.

you do not need a login https://www.binance.us/spot-trade/one_eth try typing 2.5 into the ONE field. it won't work.. worked fine in all other versions

If you are experiencing issues with Firefox when viewing and entering numbers into fields, there could be a few possible reasons for this problem. Here are some troubleshooting steps to help resolve the issue:

Clear Browser Cache and Cookies: Clearing the browser cache and cookies can often resolve display issues. Go to "Menu" (three horizontal lines) > "Library" > "History" > "Clear Recent History." Select "Everything" as the time range, and make sure to check "Cache" and "Cookies" in the list of items to clear. Then click "Clear Now."

Disable Hardware Acceleration: Sometimes, hardware acceleration can cause display issues in Firefox. Try disabling it and see if it helps. Go to "Menu" > "Preferences" > "General" > "Performance." Uncheck the box next to "Use recommended performance settings" and uncheck "Use hardware acceleration when available."

Try Safe Mode: Running Firefox in Safe Mode can help identify if an extension or theme is causing the problem. Go to "Menu" > "Help" > "Restart with Add-ons Disabled." This will start Firefox in Safe Mode. If the issue is resolved in Safe Mode, then an extension or theme is likely the culprit.

obviously your not interested in checking on this .. it's not a settings issue.. I've checked the site using IE, MS edge and even Chrome works on all of those with no issue.. so i guess I'll be using one or all of those instead of Firefox.. if you had bothered to click the link and try and type something with a decimal in it. you would have gotten the same result as i did.. guess that's asking too much tho

This was fixed recently in Firefox Nightly 117 (Bug 1839572).