Seems like lemmyverse doesnt have the instance listed at all for some reason, assuming a crawling issue. I reported it on their repository. Would be new since I remember it showing the instance before
You can check in https://programming.dev/communities that programmer humor has way more active users than most communities here
The easiest way would be subscribing to the communities you want and then using the subscribed feed instead of the all feed
Some frontends (mostly the apps) have filters you can use to filter content but the main frontend doesn't currently apart from blocking the communities
An alternate thing to do could be to use the local feed in the instance that primarily has the content you want. Isnt doable for all types of content since not everything has a topic based instance for it and would require having a new account if you want to interact but theres things such as mander.xyz for science, programming.dev for programming/hardware/etc. topics, etc.