Prysm BN compatability

[OisinKyne]

🐞 Bug Report

Description

Users report a 404 error when trying to use this repo with a Prysm BN.

Has this worked before in a previous version?

Unknown

🔬 Minimal Reproduction

Use a prysm BN as the consensus layer for this repo.

🔥 Error

🌍 Your Environment

Operating System:

What version of lido-dv-exit are you running? (Which release)

Anything else relevant (validator index / public key)?

Users error report:

I queried /eth/v2/debug/beacon/states/2177152 API on Prysm and I got 404 page not found and it is not a JSON format, so it seems like Prysm doesn't support this API.
And I also tried /eth/v1/beacon/states/2177152/validators and returned a correct response. I am not very sure these 2 APIs are exactly the same but I think Prysm has 2177152 slot's data.
I believe Prysm supports /eth/v2/debug/beacon/states/{state_id} standard Beacon node API and I am trying to find which Prysm settings I miss on the document. Does anyone familiar with this?

I wonder are we sending the appropriate Accept: application/json header?