https://fba.ryona.agency/ is one website that can help, top search box searches for instances that have defederated from the one you entered, the bottom one lists the instances the one you entered defederated from.

It only shows full instance level defederation, not blocked communities though

In the meantime, if you want both reddit like and twitter like functionality, checkout kbin. Kbin federates with both lemmy and mastodon and has both magazines (their version of communities) and microblogging (like twitter/mastodon)

mind replying to the OP since most of us are on instances hes (likely accidentally) blocked?

By setting an allow list hes blocked every other instance not in his list

https://join-lemmy.org/docs/administration/federation_getting_started.html

Allowlist: Explicitly list instances to connect to. BlockList: Explicitly list instances to not connect to. Federation is open to all other instances. Open: Federate with all potential instances.

Federation is enabled by default. You can add allowed and blocked instances, by adding a comma-delimited list in your instance admin panel. IE to only federate with these instances, add: enterprise.lemmy.ml,lemmy.ml to the allowed instances section.

some communities themselves are tagged nsfw. That might cause what you’re seeing.

Just make sure any nsfw stuff you do post you manually check the box as well.