Log spam with "webresource Different query values found for key: locale (en-US / de-DE)"

[Helma Schneider]

I get thousands of log entries of the form 

2021-01-24 17:33:56,776 WARN [http-nio-127.0.0.1-7990-exec-4] <username> @I7F1CVx1053x1137889x16 1xu9slr <User-IP>,127.0.0.1 "GET /projects/<Project>/repos/<Repo>/browse/<File> HTTP/1.1" webresource Different query values found for key: locale (en-US / de-DE)

2021-01-24 17:33:56,776 WARN [http-nio-127.0.0.1-7990-exec-4] <username> @I7F1CVx1053x1137889x16 1xu9slr <User-IP>,127.0.0.1 "GET /projects/<Project>/repos/<Repo>/browse/<File> HTTP/1.1" webresource Different query values found for key: locale (de-DE / en-US)

Note the alternating (de-DE / en-US) - (en-US / de-DE)

These entries appear for the same user, for the same path >50 Times (not always the same amount of repetitions) in a row. Then the log behaves normal for a random amount of time, and the same thing happens again for a different user/path. 

I could not find any details about this issue and hope someone can give me a hint what could be wrong.