Not currently able to filter by bundle without receiving an error message.
It may seem odd to use a cross-bundle resource and still filter by bundle, but it's very possible that you have 5-10 bundles and want to limit it to 3 or something along those lines.
Postponed
1.0
Code
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It's likely this issue predates Contrib.social: some issue and comment data are missing.
@andreic Try jsonapi/node?filter[type][condition][path]=type.meta.drupal_internal__target_id&filter[type][condition][operator]=IN&filter[type][condition][value][]=event_card&filter[type][condition][value][]=podcast