sshhhhhhhh ... it is still safe over shock level, within reason ....
The higher your FC relative to your CYA, the more active chlorine in the water and thus the more harsh it is to your skin, hair, swimsuit, etc.
Check out this chart that shows the active level as a function of CYA and FC. You can draw your own conclusions about what is a "safe level" of FC when you remember that a public pool with 0 CYA often has a FC up around 2ppm.
https://www.troublefreepool.com/~richardfalk/pool/HOCl.htm
I will give an example:
That public pool would have an active chlorine level of around 1.00ppm
At CYA 50, normal FC level is 6, giving an active chlorine level of 0.05ppm (1/20th as harsh as the public pool)
At CYA 50, shock level is 20, so active chlorine level is 0.30ppm (1/3 as harsh as the public pool)
At CYA 50, to match the active level in the public pool, the FC would need to be up around 30ppm probably.