The best conclusion I could think of is that my problem was a consequence of caching (as you stated) further complicated by some time delay (the time it took to remove Cloudflare). I also observed that I likely misunderstood your instructions. Specifically, the sequence 2, 3 and 4 in the article https://github.com/adriatic/screenshots/issues/34 have the same effect as step 2 alone.
In other words, step 2 is sufficient to disable the title on the page “Help” – steps 3 and 4 do not do have any effect on the title of the “Help” page.
At this point, I am happy with this solution and am leaving up to you whether you want to continue this discussion (to make sure that there is no bug in your code).