I like that misskey.io is getting more popular lately but it really is showing the problem of big instances - you will have trouble defederating from them even if they have completely different moderation policy that allows things you wish you could fediblock your way from completely.
I should add that the things in question may even be illegal in country where some servers are hosted, like loli/shota content, so admins of that servers are forced to choose between blocking a lot more users from federating than actually needed, and disabling proxying media while still leaving legal uncertainity.
Solutions I can think of:
- Trying to peacefully ask to move such content to more niche themed servers for easier defederation
- Trying to completely ban that content (they will still exist in said niche servers amd freespeech servers)
- Not using big servers and encouraging others to move to smaller servers that suffer less from other small servers defederating them based on moderation policy (questionable content… would still move to smaller niche servers, even if they will not be themed)