Could not process backward download of blocks: chain length exceeds limit

#### System information
```
./erigon --version
erigon version 3.3.10-e7de183d
Debian13
mainnet
./beacon-chain --version
beacon-chain version Prysm/v7.1.3/b5311502a54701f1cf1ff6f2c342e40300dd0330. Built at: 2026-03-15 19:35:48+00:00
```

### Problem

```
erigon --chain mainnet --snap.keepblocks --db.size.limit 15TB --db.pagesize 16KB --prune.mode archive --externalcl --nat none
```

Syncing from genesis got stuck at `24 767 999` with error :
```
Apr 08 13:23:27 backend8 sh[2446107]: [WARN] [04-08|13:23:27.458] [EngineBlockDownloader] could not process backward download request hash=0xd4b889e277f13158847a3474a3b75bff16c38b5ba544b7a037e6d0d303dbb76a trigger=NewPayloadTrigger chainTip Num=24832932 chainTipHash=0xa4b7265676d32337b607cb711f8653ea9194f47e233288623b0a5e71175f4f24 err="could not process backward download of blocks: chain length exceeds limit: num=24832931, hash=0xd4b889e277f13158847a3474a3b75bff16c38b5ba544b7
```

For hours already