protected boolean shouldUsePostMergeRules(
      final BlockHeader header, final ProtocolContext context) {
    if (context.getConsensusContext(MergeContext.class).getFinalized().isPresent()) {
      // if anything has been finalized, we are now using PoS block validation rules forevermore
      return true;
    }

    Optional<Difficulty> parentChainTotalDifficulty =
        context.getBlockchain().getTotalDifficultyByHash(header.getParentHash());
    Difficulty configuredTotalTerminalDifficulty =
        context.getConsensusContext(MergeContext.class).getTerminalTotalDifficulty();

    if (parentChainTotalDifficulty.isEmpty()) {
      LOG.warn("unable to get total difficulty, parent {} not found", header.getParentHash());
      return false;
    }

    if (isTerminalProofOfWorkBlock(header, context)) {
      // ttd block looks like proof of stake, but is the last proof of work
      return false;
    }

    if (parentChainTotalDifficulty
        .get()
        .add(header.getDifficulty() == null ? Difficulty.ZERO : header.getDifficulty())
        .greaterOrEqualThan(configuredTotalTerminalDifficulty)) {
      return true;
    } else { // still PoWing
      return false;
    }
  }
Should use post merge rules.

@param header the header
@param context the context
@return the boolean
consensus/merge/src/main/java/org/hyperledger/besu/consensus/merge/headervalidationrules/MergeConsensusRule.java