I found this doc page, the links don’t work but this is the kind of widget I’m finding impossible to create now: https://developer.twitter.com/en/docs/twitter-for-websites/timelines/guides/search-timeline
When I got to https://publish.twitter.com/ and enter a hashtag it only displays the option to create a button widget. When I add a search url with a hashtag for example https://twitter.com/search?src=typd&q=%23millionsteps it give me the option to create en embedded timeline widget but when I choose the option I get the following error message: Sorry, we can’t create an embed for that. It may have been deleted or made private. Please try again.
Any hashtag search timeline widget previously created still works though for example on this site: https://step.diabetes.org.uk/