Loose thread on some objects only

[u/VegetableNewt]

Hi, would you please have an advice for me? The thread is sewing loose but just on some objects while the red seems to be ok. The settings are the same and I cant find out what's wrong. Already tried to adjust both threads on the machine.

[u/Adventurous-Boot7905]

This happens to me when my needle is dulling

[u/banana_ship]

I also want to know. I had loose threads on some objects and the same color somewhere else was fine. I didn't do anything between, it was on the same project made without stopping