Main breaker question

I’m looking at a 100 amp, Square D panel. The cover cannot be removed due to blockage by fireplace.

The main breaker’s two levers are missing the cap that ties them together.

Is this a noteable problem? What is the hazard?

Big defect. Main breaker needs to be replaced ASAP

I agree with a bit more added Service is not accessible and main switch needs repair as breakers are not tied together example one half can be turned off and other half is still alive is still alive ,
Recommend immediate repair by a qualified person.

(" Is this a notable problem? What is the hazard? ") Good question

Yes two pole breakers must break both lines at the same time .
A person could think they have isolated the system by throwing the breaker and 1/2 could still be on and cause some one to be electrocuted .

I have never seen a Square D main that needed a tie bar. Do you have pics?

Improper work space. Move panel to approved area. Consider upgrading system to 150 to 200 amps to meet todays needs.

In lieu of moving the box - remove the fireplace.