Environment:
Browser / Version: Firefox Nightly 88.0a1 (2021-03-16)
Operating System: Windows 10 Pro

Prerequisites:
ETP - Strict enabled.

Steps to reproduce:

1. Navigate to https://info.tensarcorp.com/tensarsoil-software-solution
2. Scroll down the page and click "Ready to Request TensarSoil?" card.
3. Observe the form.

Expected Behavior:
The form is displayed correctly and can be filled and submitted.

Actual Behavior:
The form is broken, fields are not visible.

Notes:

1. Screenshot attached.
2. The issue is not reproducible with ETP - Standard.

This is also broken in standard mode. If I click the link before the page finishes completely loading, it works (or sometimes when I have the debugger open). If I wait until the page has completely loaded, it breaks. When it breaks, the iframe for the form ends up being 5px wide:

<iframe id="hs-form-iframe-0" class="hs-form-iframe" scrolling="no" style="position: static; border: medium none; display: block; overflow: hidden; width: 5px; height: 500px;" width="5" height="500"></iframe>

When it works, the width is set to 526px on my end. So this is almost certainly a race condition, possibly because they aren't waiting for the iframe to properly load before setting its width (it smells like another async iframe loading issue). Either way, it's probably a webcompat issue, not an ETP one, so I'm going to mark it as such.

Needs Triage.

I was able to reproduce the issue. The form from the link is broken, regardless of the status of the ETP

Tested with:

Browser / Version: Firefox Nightly 92.0a1 (2021-07-13) (64-bit)
Operating System: Windows 10 PRO x64

The layout has changed, and the "Contact" form is displayed correctly now regardless of the ETP status.
https://prnt.sc/7OtRM1MHFnKC

Tested with:
Browser / Version: Firefox Nightly 103.0a1 (2022-06-26)
Operating System: Windows 10 Pro