I think this is due to a broken nginx (or whatever reverse proxy you’re using) configuration.

Doing a GET request to https://beehaw.org/c/technology with the header

Accept: application/activity+json, application/ld+json; profile="https://www.w3.org/ns/activitystreams",application/json

is giving me an HTML page instead of the expected JSON.

For comparison, here’s what the same query responds with for lemmy.world (shortened since it’s quite a long response):

{
	"@context": [
		"https://www.w3.org/ns/activitystreams",
		"https://w3id.org/security/v1",
		{
			"lemmy": "https://join-lemmy.org/ns#",
			"litepub": "http://litepub.social/ns#",
			"pt": "https://joinpeertube.org/ns#",
			"sc": "http://schema.org/",
			"ChatMessage": "litepub:ChatMessage",
			"commentsEnabled": "pt:commentsEnabled",
			"sensitive": "as:sensitive",
			"matrixUserId": "lemmy:matrixUserId",
			"postingRestrictedToMods": "lemmy:postingRestrictedToMods",
			"removeData": "lemmy:removeData",
			"stickied": "lemmy:stickied",
			"moderators": {
				"@type": "@id",
				"@id": "lemmy:moderators"
			},
			"expires": "as:endTime",
			"distinguished": "lemmy:distinguished",
			"language": "sc:inLanguage",
			"identifier": "sc:identifier"
		}
	],
	"type": "Group",
	"id": "https://lemmy.world/c/technology"
}