A number of gunmen hailing from al-Tanf surrendered to the regime with their vehicles and weapons. There are several reports on what happened:

https://twitter.com/MaghaweirThowra/status/1250205887458938882
-MaT (Maghaweir al-Thowra)/Revolutionary Commando Army, the tiny rebel group which shares the zone with American troops, claims the convoy cannot be considered one of their own as it was led by a local drug dealer who gave up after MaT prevented him from doing his trade, leaving with his family including some MaT members. Previously they have claimed they interdict the drug trade in the highway and Hezbollah is involved, but do not link the dealer with Hezbollah.
https://twitter.com/Mzahem_Alsaloum/status/1250340393389973506
-A former MaT spokesman as "Ghanam al-Khudair" aka "Abu Hamzah Asha'ir" and claims he is a MaT member and drug dealer with Hezbollah, regime and MaT ties who was protected and given a high rank by the MaT leadership but had to leave with his retinue after local hostility made his position unsafe.
https://sana.sy/en/?p=190136
-Official Syrian media says Abu Hamza was a disillusioned MaT member who defected after seeing that within al-Tanf "militants" were being trained to sabotage infrastructure in the desert and equipment was indirectly reaching ISIS. No mention of drugs at all.