Sorry about the poor experience. We can get this checked. Is this happening only with h.264/h.265 format or is it happening with other formats as well? Also, have you tried importing the exported video in Premiere Pro and checked if it's playing properly in Premiere Pro.
Going from 59.94 fps to 25 fps will always look bad. Going from 59,94 fps to 29,97 fps will look bad as well but will look a tad better, iow not have a noticeable jump every second. It´s the same with 50 fps footage, it will look bad when exported to 29.97 and only a tad better when exported to 25 fps.
This is the nature of video, so if you want good looking 25 fps exports, use 25 fps source footage. I should also add that it can look acceptable if you use dedicated hardware to do the frame conversion but it is very expensive.
The more motion there is in the video, the more noticeable it will be. Changing codec won´t help since this boils down to mathematics.