When processing transactions, the speed is limited, only 4.6 transactions per second, so it is limited and depends on other networks to make transactions.

Blockchain is not only about Bitcoin and Defi. Even in Defi , networks that followed Bitcoin have solved scalability issues to a great extent.

make payments for high energy costs, which sometimes puts pressure on the environment

Yes , the financial tokens that follow proof of work algorithm have to face such issues. But the good thing is that majority of the networks follow other consensus algorithm that are energy effective.

Sometimes there are cases of intrusion by cybercriminals that affect the privacy of participants.

You are right. Despite high security cyber attacks have been seen on networks . But the good thing is that it is comparatively secure than our conventional system.

Nice and informative post .