The desc explicitly states this is the count of IPsec compression errors, failures during the outbound compression step, the send-direction mirror of cpvIpsecDecomprErr. Unlike a decompression error, which corrupts inbound data, a compression error here means this gateway itself failed to prepare outbound data properly before encrypting it, showing up as this gateway failing to send certain packets over that tunnel rather than the peer receiving corrupted data. e.g. cpvIpsecComprErrors incrementing after a memory allocation failure during compression of an unusually large outbound packet, the kind of pool exhaustion the fwHmem64 counters elsewhere in this MIB are designed to reveal.