Can someone point out the faults in this?

Sounds like the first floor joists are not level and joist bearings are unseucre which is stuctually unsound (not good)

With out pictures it’s hard to tell but you shouldn’t have any loose bricks, normally floor boards are laid staggered but are usually fixed by glue and nails sometimes screws there should be a ten to twenty mm gap around the perimeter of the floor boards. Hope this helps

loose blockwork not a prob sounds like bit of shrinkage need longer screws into joist would b surpised if joist were that far out of level either way can easily b sorted so dont panick

You shouldn't have any loose bricks. You may have problems with cracks in your wall later duo to shrinkage of the building, the couse of that is usually poorly done foundation and cousing the buoldings one side is shrink more then the other... and then u have loose bricks, or those bricks got knocked off, then someone just moved them back in to the place, and they lost adhesivity with muck or flooring boards do not have enough space around the perimeter 10mm-20mm should be standard for the movement of timber. Badly fixed joists are not a big deal as they can be easily fixed. Its hard to say without pictures. However, good luck to you. Hope it helps.