I was using Clearfy plugin these last months and have deactivated it just now. Otherwise, I use Cloudflare. I purged the Cloudflare cache this morning. As of now, the website homepage will still appear correctly just once on any browser. It has been like that for ever, to my mind, or maybe since I started using Clearfy and there was some conflict with Cloudflare.
I read somewhere that Cloudflare might take 24 to 48 hours to implement the last version of the website on all its servers. Maybe I should just wait?
One more thing I should mention: the homepage has never ever appeared properly, under any circumstances, when clicking “Visit Site” from the WP dashboard.
I have purged the whole Cloudflare cache again. The website homepage appeared properly once in Brave browser in private mode, as it usually does, and impropely with all other browsers, even in private mode.
It seems to me that the homepage appearing properly just once and only in incognito mode is a clue.
Holy crap! It works. Does that mean that masonry cannot be used?
Fixed Widget plugin and Add to Any plugin won’t work properly, either on pages or posts for the first one and depending on the browser, and nowhere for the second one. I guess I will have to reach out to their developers.