Um… no, that’s not the case at all. There is certainly knock-on effects from gerrymandering, especially of the kind found in Texas, which was highly aggressive in nature (and implemented with veiled threats to Democratic voters). People who don’t believe that their vote will have any impact locally, will often not come out to vote at all, meaning that they are less likely to come out for statewide elections.
It’s a return of Jim Crow principles, where race was never explicitly stated in state laws, but were employed to keep Black voters out of the voting booth, in part by making voting as pointless as possible, and giving the state cover for denying Black voters the ballot.
These are not discrete fields that have no impact on the other. They are connected, and gerrymandering IS a form of voter suppression that should go, because of it’s impact on all elections. To say other wise is to misunderstand what is happening with the attack on voting.