This may be the same problem we discussed in Caddy HTTP/3 (QUIC) and the new Apple Software today . It’s an issue with HTTP/3 on iOS18. It didn’t affect iOS17. It’s fixed in the master code, what will become Caddy 2.9.0, but is currently broken in 2.8.4.
It mainly seems to affect things written in Go like Miniflux, likely because Go doesn’t always send the Content-Length header in responses back to the client.