Kafkacat would read less records than expected

[YordanPavlov]

So this is most probably, some lack of knowledge on my part, but when reading a topic from start to finish with Kafkacat I would expect the number of records read to match exactly the offset of the topic reported. The only reason for reading less that I could think of is non commited messages, that's why I specify the 'read uncommitted' flag. Here is the command:

kafkacat -b blockchain-kafka-kafka-0.blockchain-kafka-kafka-headless.default.svc.cluster.local:9092 -C -t my_topic -p 26 -K: -e -X isolation.level=read_uncommitted | wc -l
% Reached end of topic my_topic [26] at offset 498376: exiting
441825

As seen, the last offset seen is 498376, that's also the value I would see if I use the Kafka console tools:

kafka-run-class.sh kafka.tools.GetOffsetShell --broker-list KAFKA_URL --topic TOPIC --time -1

However, only 441825 records are shown. What is the reason behind this, the version I use is this:

Version 1.6.0 (JSON, Transactions, librdkafka 1.6.0 builtin.features=gzip,snappy,ssl,sasl,regex,lz4,sasl_gssapi,sasl_plain,sasl_scram,plugins,zstd,sasl_oauthbearer)