I found if I set my pots on concrete like that even with carpet my pot temp was too low.
Cool pot temps make it harder for roots to up take nutrients properly.
Effected growth aswell
Once I raised them off the ground it helped with the issue.
Pot temp should be 18c minimum.
A piece of Styrofoam sm underneath would really help.
But anything to get them off the ground would be beneficial to you.
Little things make a difference.
Bill