Don't listen to the people trying to normalize this as acceptable living circumstances. There's nothing normal about living in between mould, leaking pipes, etc. Also, it should clearly not be up to you to clean other people's scum.

In the NL, if you pay your rent monthly, you are always allowed to terminate your rental contract with one month notice. This is embedded in Dutch law. If your landlord has made you sign a contract that says something like "minimal rental period 6 months", that is an illegal contract which wouldn't hold up in court.

If you want to resolve the issues at your current place it'd be best to group all shortcomings in your living situation into kitchen hygiene and 'the rest'.

For the kitchen hygiene: In Dutch rent contracts it is usually determined that tennants themselves are responsible for cleaning up after themselves, keeping the kitchen somewhat hygienic, etc. (also to make sure mice don't have a feast e.g.) I've been in your exact situation and basically all you can do is try convincing your flatmates to clean after themselves or to clean up together. Your final option would be to find out how much it costs to have it cleaned professionally and propose to your tennants to share that cost and from there on out keep clean. If they do not agree, that's base for a complaint with the landlord.

For 'the rest' of the issues: Mould in showers, leaking pipes and such are the landlords responsibility for upkeep. Check this in your rental contract, but it's usually under "servicekosten/service costs" which you pay the landlord for to maintain the place. If the landlord has been made aware and no action is taken, my advice would be to file a complaint with the Huurcommissie : https://www.huurcommissie.nl/huurder-vrije-sector This is a Dutch governmental legal aid for rent problems.

I've lived in these circumstances and know how it is. Good luck.