Last year we finally saw the record of the 88 car (mp4/4) being broken at % of wins. So predictability has been around for quite a while already. But true reliability was surely an issue in the 90's and early 0-s. But more so punishing tracks helped to get unpredictable results. Nowadays we barely have gravel traps where a car gets stuck (and if it does we immediately have a sc or red flag depending on the mood of race control). To me that is where the problem lies mostly.
We always have had dominant cars (Mclaren in the 80-s, Williams in the 90-s, ferrai in the zero-s, Redbull and Mercedes in the 10's and now again redbull), but we never had a set of tracks like we have now with the extensive run off areas. But with that also comes the discussion of safety. We've seen horrible crashes in the worst cases resulting in the death of a driver, marshall or spectator. I for one don't want to have those back at the expense of having a more unpredictable result.
Getting refuelling back would be fun for strategies, but thats against the "durability" agenda. If tires wouldn't be an issue anymore in the race I doubt that would change much. Now they drive to delta, but if they could push every lap I doubt yesterday results would have been different, maybe even worse given the fastest lap was 1.4 seconds faster then the 2-nd fastest.
I don't have an answer unfortunately and I don't think much will change. In 2026 we get a new engine ruleset, the team having done that the best will dominate the start of the next era.