Sulpher is added to the natural gas at its origins - a safety feature both to gas transmission personnel and consumers. Perhaps there is some breakdown in processing...?
COVID is known to cause long term loss of smell...and there are findings loss of smell via the covid vaccine.
https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2817869
https://www.nia.nih.gov/news/lingering-covid-virus-tongue-linked-long-term-taste-loss
might contribute ?