If one read Martin Fowler about feature branching, https://martinfowler.com/bliki/FeatureBranch.html and articles from Jez Humble both agree on that one should use trunk based development and use feature toggles in most cases for development.
Seriously, this is the quintessential Gentoo Linux problem. Nobody can test all the combinations making the flags almost instantly useless. (And some essentially forced on.)
But I can definitely see too many feature flags leading to a byzantine web of untestable combinations.