admin-ajax overloading server′s resourses CPU and memory

Hi,
since November 15th i had an overloading issue and couldn′t find the problem. Weather was displayed perfectly but yesterday i realized i had many ajax calls with 500 error. I deactivated the plugin and the problem got history. This happened before and after updated WordPress to version 5, means that had not relation with the update. I suspect the matter comes from Openweather, but i decided to leave a precedent, so i may help others.