Deadlifts are not BAD for your lower back. Your body is designed to hip hinge and lift loads in this position.
Your spine is safe (assuming form is good) and compression on the spine is perfectly normal and safe within normal situations.
Now there are situations where deadlifts (in my opinion) become bad for your lower back.
If you are constantly in pain after doing them but refuse to give up these exercises then yes, deadlifts are bad for YOUR back.
If you lift more with your ego than your brain and refuse to address the constant back pain you have with exercise then yes deadlifts are bad for YOUR back.
Can you see the pattern here?
There really isn’t one exercise that is bad for your body but when applying a specific exercise to different people you will get different responses and with those responses, you need to determine whether or not that exercise should continue to be used if long-term health and happiness are at a risk.
Saying deadlifts are bad for your back because your back hurts when doing them is like saying bicep curls are bad for your elbows if your elbows hurt…you need more context to make that claim.