Probably try those filtering options under Input Processing (I think) as a first port of call.
However, based on my recent experience I’d definitely try different cables. Reason being, I have a Saturn SCART cable from Retro Access from 5-6 years ago (when they were EBay only and known as Retro Console Accessories). It has jailbars on flat panels via OSSC and also direct to CRT. Bought a new cable from them two months ago and Saturn jailbars are now gone. It’s known that the various cable manufacturers have improved their technical knowledge in recent years and this has lead to higher quality products.