>But it has serious long term effects which are hard to understand as it’s so complex.

This paper attempts to study it: https://www.bis.org/publ/qtrpdf/r_qt1809g.pdf, and found that artificially low interest rates create zombie firms that could not survive without such low rates, and "that zombies weigh on economic performance because they are less productive and because their presence lowers investment in and employment at more productive firms.".