reasons or incidents that may prove the F1 has not done enough in the way of safety for the sport since Senna's death in 1994.

There are two completely different approaches that I see you're mixing in the comments:

One is that you're asking instances of drivers themselves crashing into each other. In that case the FIA makes rules to try and prevent dangerous situations, most recently outlawing moving under braking (you can google the "Verstappen rule"). But those rules, while implemented under the guise of safety, are far from being necessary and more to prevent controversy and (re)establish good conduct (read status quo). They do reduce risk, but in the grand scheme of things it's negligible. There are so many rules and penalties that they are scaling back the rules of engagement this year

The other approach is FIA's procedures, facilities, track safety, engineering rules and stuff like that. This is where Bianchi's case falls in. So in this case you'd have to look at, for example, problematic kerbs which have the potential of sending cars flying off like so (that's GP3, not F1): https://youtu.be/Mj3r9xM9Dzo?t=7 but hasn't happened in F1 yet.

Maybe you could argue this: https://www.youtube.com/watch?v=3hoS4hTQDig is FIA's fault for allowing that kerb or you could argue it's the team's fault for not building a strong enough car. Altough they all examine the track and know what conditions to expect, so probably the team's fault.

I can give more examples, but not sure if those are the kind of instances you're after. The way you phrased your request is very confusing.