Allocation to much mem

Hi,

for a while now I get this error when I refresh wp-matomo in the dashboard:

Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 137438953444 bytes) in /var/www/web9/htdocs/piwik.linuxnews.de/plugins/UserCountry/functions.php on line 164

Refreshing it again makes the error go away and everything works fine. Any ideas what may cause this?

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