Damn! Of course, after posting a question, I found an answer. When running
collectstatic I’ve noticed that there was too many
Found another file with the destination path... messages, but did not take this into account. Then I realized that somehow in my core app staticfiles folder were duplicates of Wagtail’s core static files, so I installed Wagtail 2.11 for the millionth time, ran the server and nothing changed… Fortunately, I’ve guessed(thanks to @gasman) to clear cache and reload the window and IT WORKED!
Conslusion: Check for duplicated static files, mine were from the old version of Wagtail, but Wagtail is on latest, which caused this issue…
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