@Sala I’ve spent some time this morning reviewing your WordPress configuration. The issue of the duplicated h1 tag is being caused by AnsPress - you’ll no doubt recall I warned against using this “plugin” (if you can call it that - it’s terrible) here
AnsPress is well-known in WordPress circles for being one of those plugins you’d avoid at all costs. I used it once - never again. It causes far too many issues, and provided you don’t mind your site suffering as a result in terms of performance, bugs, and the like, then ok. In relation to SEO, see the below
This was reported in October 2022, and it’s still not fixed.
From my own independent review, I also see the following issues
The most damaging of these is content being served on both non-www and www URLS, which needs to be fixed ASAP. You’ll note that the h1 heading appears twice (which you’re already aware of)
However, aside from SEO, I see far more important issues that you need to resolve firstTTFB (Time to First Byte) - the page is incredibly slow to load - in some cases, it takes 2-3 seconds before any content is shown. This is a killer in itself as more than one second loading time is considered far too high. 301 redirects are missing - in this case, you should have a global redirect so that the content is being served from the same domain at all times.
The bottom line here, and the “fix” is to remove AnsPress. Clearly, this isn’t palatable from your perspective as there is significant investment on your side. I know from previous discussions that AnsPress was shipped with the theme you are using, but it’s a below-par plugin in terms of performance and stability.
You’ll see below my attempts to get AnsPress working as far back as 2017 - I promptly gave up, because it was such a mess
And finally, one very well respected WordPress resource (wpcrafter.com) parted ways with AnsPress in 2018 for similar reasons, which he clearly stated
At this point, I would weigh up the investment in AnsPress and seriously consider removing it.