Solved: Incoming activity has invalid signature

I set up my own instance and I could subscribe to a bunch of communities and get posts from them. But beyond that I'm not seeing any updates. My logs are spammed full with messages like this.

Do they think I'm on http instead of https? I'm behind Apache as a reverse Proxy. Do I have to tell them or lemmy that I'm on https?

I'm really confused because the logs indicate that the messages are at least reaching the app.

proxy_1     | 172.19.0.1 - - [08/Jul/2023:13:49:57 +0000] "POST /inbox HTTP/1.1" 400 39 "-" "Lemmy/0.18.1; +https://lemmy.ml"
lemmy_1     |    0: lemmy_server::root_span_builder::HTTP request
lemmy_1     |            with http.method=POST http.scheme="http" http.host=swg-empire.de http.target=/inbox otel.kind="server" request_id=2bb60404-bd87-4a79-95b8-2a25549b5bb0
lemmy_1     |              at src/root_span_builder.rs:16
lemmy_1     | LemmyError { message: None, inner: Incoming activity has invalid signature, context: SpanTrace [{ target: "lemmy_server::root_span_builder", name: "HTTP request", fields: "http.method=POST http.scheme=\"http\" http.host=swg-empire.de http.target=/inbox otel.kind=\"server\" request_id=2bb60404-bd87-4a79-95b8-2a25549b5bb0", file: "src/root_span_builder.rs", line: 16 }] }