The WikiWho API doesn't respect percent-encoded slashes. This is a problem when a page title ends with a slash followed by a number, since WikiWho interprets the number to be a revision ID.
For example Heuschreckenplage 2019/2020 on German Wikipedia:
https://api.wikiwho.net/en/api/v1.0.0-beta/rev_content/Heuschreckenplage_2019/2020/?o_rev_id=true&editor=true&token_id=false&out=false&in=false
https://api.wikiwho.net/en/api/v1.0.0-beta/rev_content/Heuschreckenplage_2019%2F2020/?o_rev_id=true&editor=true&token_id=false&out=false&in=false
The former understandably wouldn't work since this matches the URI scheme for getting data for a particular revision (revision ID 2020 in this case). The latter encodes the slash but WikiWho still chops off the number, hence why you get the error that "Heuschreckenplage 2019" doesn't exist.
This causes XTools to fail too, e.g. https://xtools.wmflabs.org/articleinfo-authorship/de.wikipedia.org/Heuschreckenplage_2019/2020. Downstream bug report at https://phabricator.wikimedia.org/T250489
The WikiWho API doesn't respect percent-encoded slashes. This is a problem when a page title ends with a slash followed by a number, since WikiWho interprets the number to be a revision ID.
For example Heuschreckenplage 2019/2020 on German Wikipedia:
https://api.wikiwho.net/en/api/v1.0.0-beta/rev_content/Heuschreckenplage_2019/2020/?o_rev_id=true&editor=true&token_id=false&out=false&in=false
https://api.wikiwho.net/en/api/v1.0.0-beta/rev_content/Heuschreckenplage_2019%2F2020/?o_rev_id=true&editor=true&token_id=false&out=false&in=false
The former understandably wouldn't work since this matches the URI scheme for getting data for a particular revision (revision ID 2020 in this case). The latter encodes the slash but WikiWho still chops off the number, hence why you get the error that "Heuschreckenplage 2019" doesn't exist.
This causes XTools to fail too, e.g. https://xtools.wmflabs.org/articleinfo-authorship/de.wikipedia.org/Heuschreckenplage_2019/2020. Downstream bug report at https://phabricator.wikimedia.org/T250489