oh dang.

can they fix it?

That sounds complicated and expensive

That doesn’t sound good...

Oh crap.

YOU can actually fix that pretty easily if it is just one:

Jack up the broken joist with some kind of a bottle jack or even the jack from your car might work. Once at the right height, support it by putting two new sister joists, one on each side of the split as far as they will go. Screw or bolt them into place with heavy hardware, not just nails. Then take out the jack.

make sure the joists are as big as the existing joist in size, and try to make them at least 5 feet long, but longer is better.

$50 and your done!

if it is more than one joist, do it for several. It is not a permanent fix, but its a good solid fix that should last for years.

Oh wow! It does sound complicated, and expensive, but easy and cheap when Max explains it. Good luck!

landlord is fixing it today, I think he's doing exactly what you said, Max