It seems quite clear that there is a structural bug probably linked to the latest MediaWiki update, a template/module LUA instead of giving the usual timeout or out of memory errors directly creates a denial of service with error 503.

Now I have optimized the code of [[Modulo:VociRecenti]] and the page has started working again, but I think the problem is another: to prevent the WikiMedia server error 503 from occurring, perhaps there was a recent MediaWiki update that bypassed some checks on the modules/templates or similar?

The page on its own displays without problems [[Progetto:Patrolling/Voci da patrollare]], but if I go back to include it in the [[Progetto:Patrolling]] home page the error occurs again.
From March until yesterday it worked without problems.

I emptied {{Progetto:Patrolling/Voci da patrollare}} and now the page loads, but I had implemented it a few months ago and it didn't cause problems before yesterday, so I also duplicated it here: [[User:IndyJr/Patrolling]] and it doesn't cause problems, it still works.

In T233127#5563134, @mobrovac wrote:

Update: I think I found the bug in RESTBase. I deployed the fix yesterday and so far so good. I will leave RB logging on until Monday to make sure the problem is indeed fixed.

In the meantime, I also found how to reproduce the bug, so if there are any testers willing to try it, feel free to test it out. The bug essentially happens on a first VE-edit of a page (that is, open the browser, load a page, click on edit) for pages that have been last edited more than 24h prior.

Is there any debugging tool that can be activated and can record all client/server swingers data in case of hitting the error?

It is evident the bug has not been fixed, it has only decreased frequency.

I no longer observed that bug after they (developers) claimed to have fixed it, but if it still persists today evidently the underlying problem remains.

The problem I reported still go on, on random pages, and is not reproducible. The only workaround I found to don't lose job until then, is to copy and paste into a new window that NOT recovers the unsaved work (because otherwise it doesn't save it again with the same error message).

Try to made more deleting lines and modify wikilink. The problem cannot reproduce at every single edit, but it appears very frequently.