Quality factor: relevance top - nevertheless QF=3, what to do?

Hello fellow Google Ads specialists,

in the account I manage, you'll see the same image across all campaigns:

Expected click rate > Below average
Advertising relevance > Above average
User experience with the Landingpage > Below average

I wonder why and how I can optimize my click rate and user experience.

Over a month, the CTRs of my campaigns are mostly over 3%, but even for those where the CTR is over 10% or even over 20%, Google gives me the rating "Estimated Click Rate > Below Average". How can that be, or what do I overlook?

The bad rating of the user experience is completely unfathomable to me. Almost everywhere below average, although the H1 of the target page always contains the keyword and the landing pages are clearly adapted to it. Optimization for mobile devices is satisfactory for Google, also the page speed is in the green (desktop) and in the upper yellow area (mobile).

Probably there won't be any general advice to solve the problem directly, but I'd like to get to the bottom of the problem by further questions from you and I'm looking forward to your comments!

You mentioned each landing page has different H1 text but is the content the same? It would be better to have unique content or just one landing page instead. Google isn't stupid and doesn't like duplicate content in different landing pages. Changing H1 is not close to being enough. Yes not having different H1 tags may hurt conversions but it might be offset by the increase in QS. You can also check into W3C compliance.

Expected CTR is also determined with statistical confidence. Meaning that they'll look at CTR for about the past month or longer. So is the CTR you're referring to from the past day or past month and is there enough clicks for a good 90%+ statistical confidence?