iOS18 Static Rulesets Stop Working

iOS16 and iOS17 were fine, but on iOS18, our Safari extension that blocks content via static rulesets randomly stops working. Frequently, when a tab is left in the background for a long time (i.e. hours), the content blocker will stop working (until I either kill safari, or reload the extension). I've debugged this and the background.js script reports the ruleset as being loaded, but nevertheless, our rules aren't applied.

I really don't think that it's an issue with the way that the rules are defined, since iOS16 and iOS17 worked fine, and on iOS18, the rules DO work. They just stop working after a while.

    "declarative_net_request": {
        "rule_resources": [
            {
                "id": "ruleset_1",
                "enabled": true,
                "path": "ruleset_1.json"
            }
        ]
    },

Some theories:

I have other content blockers on my phone that have LOTS of rules (adguard). Could I be seeing the effects of too many rules? Can I debug this somehow? Do logs get printed somewhere when the max rule limit is reached?
Does the use of private and regular tabs mess things up?

Please, any input is appreciated, as all of our logs are normal and error-free.