Gidey improved the WR by 70 seconds, so about 1.5%.
For a world record to be clean:
The most talented clean athlete has to be several percent better than the most talented doper (depending on the discipline and expert), despite the high abundance of dopers*.
For example, banned drug cheat coach Salazar estimated a gain of 2 minutes in the marathon, and doping experts Ashenden and Parisotto 15 – 30 seconds over 5,000 m, and Schumacher up to 60 seconds over 10,000 m (just for blood doping alone). That's 2 - 4% improvement.
If Gidey is clean, she is 3.5 - 5.5% better than the most talented doper (whoever that may be); if she is dirty, "only" 1.5% better.
* See for example Faiss et al.; Frontiers in Physiology 2020: