Redirect pdf using old single site link to new multisite

Hi there,

I am struggling to find an elegant solution for redirecting pdf files from an old single site to a newly migrated multisite. The web server is nginx and I don’t have access to a .htaccess or redirect rules. Trying to redirect a URL like this:
wp-content/uploads/2020/05/another1.pdf -> wp-content/uploads/sites/3/2020/05/another1.pdf
leaves me with a 404 page and the error:

Expected: 301:https://somesite/wp-content/uploads/2020/05/another1.pdf
Found: 301: https://somesite/wp-content/uploads/sites/3/2020/05/another1.pdf
Something else other than Redirection is redirecting this URL.

Other than asking my host to create individual rules is there something I can do using the plugin or my host could use with a regular expression?

Thanks

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