As you have read in the ATG Guide to Olympic Qualification:
Countries whose athletes have consistently been popped will lose spots. Or, framed another way, all countries (NOC/MF) start with two spots (one man, one woman) and countries with better WADA records earn more spots (subject to the IWF Anti-Doping policy), up to the eight total possible lifters.
The IWF released (see PDF here) the updated Olympic quotas for Tokyo 2020 with the current doping cases (some are still being processed):
Additional Reading: Read about the re-test positives from past Olympics.