in here! so:
1. DURAFLEX QUIK-SLIP KEEPER, comes in 20mm (which is what you will need for the jacketsling (if they haven't changed since last time I bought ACR jacket - SS12). imo it's a bit too big solution for the low-profile jacketsling but it's the easiest to operate. Other manufacturers (woojin, ITW) will have alternatives too.
2. ITW WEB DOMINATOR. Only comes for 1'' but the construction is weird anyway.
3. ITW ANNEX CLIP. Only for 1'' and I do not like how stiff it is. The aliexpress versions work better from my point of view (search keyword: "webbing clip")
4. Good'ol SLOTTED LOOP is meant to be securing loose ends even when we use it to attach pouches to PALS rail. Comes in 20mm too.
5. My prefered would be a DIY solution. Simple elastic band folded, sewn and turn inside out. While at it, I would replace the default (again based on SS12 jacketsling that still had the fidlocks inside) elastic strap with a stronger one.