A simple bash-script to easily monitor if a directory has grown or shrunk in size:

while [ 1 ]; do result=$(du -s * | egrep "bitcoin-0.21.1$"); echo -e "\e[95m$result\e[0m"; curSize=$(echo $result | cut -d" " -f1); if [ $curSize -lt $oldSize ]; then echo -e
 "\e[92mShrunk: $curSize\e[0m"; else echo -e "\e[91mGrown: $curSize\e[0m"; fi; oldSize=$curSize; sleep 5; done

Script needs to be executed in the parrent directory of the monitored dir and directory name must be adapted: bitcoin-0.21.1$ -> to whatever you want to grep for