Editing a PDF form on the Dropbox website shrinks field length as you zoom in

I have an issue with a PDF form (that I didn't create) that allows you to enter text to fill the visible space but if you zoom in, that length reduces until at say 400% it will only allow 4 characters but a full name at 100%.

It works fine in Adobe Reader allowing the same amount of characters regardless of zoom, typing until you hit the end of the field box.

In Drop box the font matches the document as you scale it, but the field length appears to be incorrectly constrained by a physical length instead of one that scales with the % selected.

I've tried on a couple of machines but I don't have a creator handy to make a doc with a visible field only (I guess to enable no clipping of info when printed) to see if it happens with something I made rather than just their document.

I'm guessing the document has something like "Scroll long Text" disabled for the fields.
I'm also guessing that possibly Dropbox's internal PDF Editor is restraining the text entry to a length at 100% regardless of the actual view %. (I'm simply opening the document from within Dropbox with the EDIT options available to the file.)

I'm using Chrome via Win10 machines.

[I'm a rusty ex Dell cert, Fujitsu, EDS IT Tech from Y2k, back when the web gave all answers, not all adverts.    Tip of the day... Did you know you can SHAME AI like Copilot into giving a better answer... just ask if that was the best it could do when using it... I'm betting its A CPU time per question that comes up with the 'I can't be bothered answering that one right now']