DTTG capture issues in Firefox (edit: and Safari)

I am having problems capturing web pages on my iPad Pro 12.9 (2021) from my preferred browser, Firefox.

Many web pages are not captured at all or only as rich text. Bookmark capture is not even possible.
DTTG version is v3.1.1, iOS 14.6, Firefox version 34
Here is an example of a web page that can not capture as bookmark or web archive from Firefox:

Do I need to change certain settings in Firefox to enable capture?

Edit: Although the capture menu pops up in Safari, the clip is not saved in DTTG

It’s working OK here with Safari. The only suggestion I have is that you restart the device. There have been intermittent issues with sharing in IOS/iPadOS 14, including with DTTG