What does redis cache in the Gitlab?

I have generated a list of keyspaces along with their size and ttl (715 keyspaces) and trying to analyze which keyspace is consuming huge memory. I can see that total memory occupied by the keyspaces is 1.2 MB but my Redis PVC is filled up to 13 GB. So, what is occupying so much memory in Redis container ?

Redis Version: 6.0.9 Image: bitnami/redis:6.0.9-debian-10-r0

Script I used to generate the list:

#!/bin/bash

NAMESPACE=$1
SECRET=$2
POD=$3
CONTAINER=$4

PASSWORD_REDIS=$(kubectl get secrets -n $NAMESPACE $SECRET -o jsonpath='{.data.secret'} | base64 -d )
kubectl exec -it -n $NAMESPACE $POD -c $CONTAINER -- redis-cli -a ${PASSWORD_REDIS} KEYS '*' | tail -n +2 > keylist.csv
    keylist.csv

declare -a KEYS;
arraylen=0;
i=0;
j=0;

test2(){
    arraylen=${#KEYS[@]}
    echo "kubectl exec -i -n ${NAMESPACE} ${POD} -c ${CONTAINER} -- redis-cli -h 127.0.0.1 -a ${PASSWORD_REDIS} MEMORY USAGE ${KEYS[j]}" > keys.sh
    chmod +x keys.sh
    ./keys.sh > size.txt 2> /dev/null

    echo "kubectl exec -i -n ${NAMESPACE} ${POD} -c ${CONTAINER} -- redis-cli -h 127.0.0.1 -a ${PASSWORD_REDIS} TTL ${KEYS[j]}" > ttl.sh
    chmod +x ttl.sh
    ./ttl.sh > ttl.txt 2> /dev/null

    SIZE=$(cat size.txt)
    TTL=$(cat ttl.txt)
    ((j=$j+1))
    echo "$j,${KEYS[j]},${SIZE},${TTL}" >> output.csv
    if [ $j -ge $arraylen ]; then exit
    fi
    test2
}

while IFS=') '  read -r slno line; do
  LINE=${line};
  KEYS+=([i]=$LINE)
  i=$[$i+1]
done < keylist.csv

test2

Output looks like this (3rd column is size in bytes and 4th column is TTL in ms):