Thanks @Inselaeffchen
I was able to reproduce this and have prepared a fix in https://github.com/matomo-org/wp-matomo/pull/436/files . In case you are familiar with PHP or patching files you could apply this patch to wp-content/plugins/matomo/plugins/WordPress/Logger.php .
Basically, there was an incompatibility with their plugin where they were using some similar naming but had a different implementation causing things to execute in a never ending loop. The patch should fix this and it should be included in our next release.
Thanks for reporting this!