The limit is 330000 rules:
"Based on input from the extension community, we also increased the number of rulesets for declarativeNetRequest, allowing extensions to bundle up to 330,000 static rules and dynamically add a further 30,000." https://blog.chromium.org/2024/05/manifest-v2-phase-out-begi....
It looks like it’s a shared quota now with a minimum per extension [1].
Still sucks that the rules are static though. AdGuard devised a method to diff ruleset changes with the built in rules to generate dynamic rules between extension updates. So, I guess it works.
[1] https://developer.chrome.com/docs/extensions/develop/concept...