The following error is appearing:
[error] 11927#11927: *283886967 FastCGI sent in stderr: “PHP message: PHP Warning: urldecode() expects parameter 1 to be string, array given in /var/www/matomo/plugins/Referrers/Columns/Base.php on line 188”
I have noticed matomo is picking last one and discarding the first one in normal case i.e. without “[]” and matomo shows URL in visitor log after excluding utm_campaign .
Though with “[]” in utm_campaign, campaign does not get logged at all and above error is appearing .
Matomo only supports one campaign per tracking call, with [] the parameters is an array and not supported (expects parameter 1 to be string, array given) with multiple campaign-parameters only the last one counts.
I tried to convert your call to an actual Matomo campaign: https://example.com/?pk_campaign=EMAIL_CAMPAIGN&pk_kwd=countries&pk_source=e-news&pk_medium=e-mail&pk_content=appeal19