If remaining altitude indication is unreliable: Do not use FPV and/or V/S which are affected.
and
If remaining altitude indication is unreliable: Do not use FPV and/or V/S, which are affected.
These statements appear to create an English grammatical juxtaposition, and the intention (IMO) is to state,
"If remaining altitude indication is unreliable: Both FPV and V/S are affected, and must not be used."