FLStudio ASIO driver. This seems to have happened after I installed FLStudio 20, all though I used it when recording a video about the FL20 beta, which worked fine. I did a search and found a similar post ...
I found a bug related to rendering selection of the tail when rendering;
If you select wrap reminder you get very noticable crackling in the sound and distortion on the transients. I have no idea how it was related but ...