You might open our product catalogue download page with the online form disappeared (like below image).

This is because Firefox has a concept called Enhanced Tracking Protection. As our online form is embedded on the page by source code, Firefox implements its protection on this page and blocks the form.

If the form is disappeard/blocked, try turning off Enhanced Tracking Protection. It allows trackers to load on that site only. Enhanced Tracking Protection will continue to block trackers on other sites.

Please follow the below steps to unblock the form.
1.Click on the shield shield to the left of the address bar.
2.Toggle the switch at the top of the panel.

• This will turn off Enhanced Tracking Protection for this site. The page will reload automatically and allow trackers on this site only.

Reference link