Someone on Facebook claimed that tourists who were unable to leave Spain due to COVID were declared tax residents if their stay was over 183 days. I haven't been able to find such a case in a web search, but that's not a refutation, since the search terms required appear in thousands of unrelated pages.
I would appreciate a citation if someone is aware of a specific case of a visa-exempt 90/180 tourist without padrón being taxed by Spain due to an overstay caused by COVID restrictions. Or other overstay. (Income tax, not fines for the overstay.)
Padrón is the registration of address required within thirty days of arrival if you are on a visa that implies intention for permanent or temporary residence.
UPDATE: This looks pertinent: https://www.surinenglish.com/local/202010/02/concern-month-obligation-ruling-20201002104434-v.html but it doesn't say they were actually taxed, and they are Lebanese, who aren't 90/180 visa-exempt. It also refers to "second-home owners," so it's too vague to really answer my question.