Looks good to merge. There are a few comments re this filter and that it maybe behave a bit more strict or so but the comments are old and I reckon it's fine 👍 https://www.php.net/manual/en/filter.filters.validate.php
Before merging though could you remove the code from here @Findus23 https://github.com/matomo-org/matomo/blob/3.10.0/config/global.php#L203-L209
and I reckon we could also remove the zend class itself? It doesn't seem to be used
I guess one day we should be removing all of those zend classes and replace them with modern libraries.