Article Limpopo is apparently an exception to CosmeticChangesToolkit.standardizePageFooter's definition of a category main article.
There should be a way to prevent the bot applying cosmetic changes on a page, but still allow editing it.
Proposal: Reuse {{bots}}/{{nobots}} for this. Where {{Bots|denyscript=cosmetic_changes}} would be matched, cosmetic changes would be skipped.
Solution: After https://gerrit.wikimedia.org/r/c/pywikibot/core/+/697138 is merged, add module argument to BasePage._check_bot_may_edit. It would default to pywikibot.calledModuleName(). Then, cache self._check_bot_may_edit('cosmetic_changes') separately.