You've gotten great advice on how to get rid of the loops on the back. Most often these loops are caused by bobbin backlash and are not a tension issue (which can present like eyelashes or pokies). Backlash can happen when you change speed or direction very abruptly. The bobbin continues to spin causing the loop to form on the back with the next stitch. Some longarms/midarms have an antibacklash check spring in the bobbin case to help alleviate the issue.
https://thelongarmnetwork.com/anti-backlash-spring
Other things that help reduce bobbin backlash are washers or disks to help keep the bobbin from freely spinning when coming to an abrupt stop
https://thelongarmnetwork.com/anti-backlash-disks https://www.amazon.com/s/?ie=UTF8&ke...l9ga5d2j_e_p38 , maintaining consistent speed of the machine head when changing directions, or my favorite which is to use magnaglide prewound magnetic core bobbins
https://www.amazon.com/s/?ie=UTF8&ke...7se29t01_e_p38