Thank you for your question.  Please check your linden to see if the trunk flairs out just before before it inter the soil. If it does not flair out your tree may have stem girdling roots. Lindens are an important source of bee nectar. Bees are  aware of the sweet nectar that is released from the
flowers to attract them for their pollination services.  Please go to the next site. Their are several insects that can cause linden trees to turn yellow. The pictures are not clear enough for me to identify the insects but aphids and lace bugs have piercing/ sucking mothparts that cause linden tree leaves to turn yellow.   Please examine  your tree leaves for insects.   The following site may help you diagnose the problem.
https://extension.umn.edu/yard-and-garden-insects/lace-bugs
https://apps.extension.umn.edu/garden/diagnose/plant/deciduous/linden/leavesspots.html