Could you send a screenshot to show us what you mean?

Here is the screenshot - it happens on all the devices that I have tested.

Under the text box is a field which I can not see what I am entering

I've just tried it on Nightly (I can't seem to load it on the normal build), it seems to work fine so I'm guessing the issue will be fixed soon.

Has this issue happened on other sites? and (you probably have) have you tried scrolling down more?

upon closer inspection, this only seems to be an issue in the Progressive web app which is downloaded and run on the firefox browser

File a bug report here ➡ https://bugzilla.mozilla.org/

By the way, this would be better in the mobile section:

@clark5 I wanted to say a massive thank you for your support. I have followed the advice you have suggested and logged it with https://bugzilla.mozilla.org/, hopefully, there will be a positive outcome as I'm still awaiting a response.

Thanks