What is genuinely inherited
Data availability and settlement. Because the rollup publishes enough information to Ethereum for anyone to reconstruct its state, you do not need the rollup operator's permission to prove what you own. In principle you can exit even if the operator stops cooperating.
That property is real and is the reason rollups are treated differently from sidechains, which have their own validator set and their own security entirely.
What is not inherited
Liveness and ordering. Almost every rollup today runs a single sequencer, which decides transaction order and can go offline. During an outage the chain stops for everyone, and Ethereum cannot help.
Upgradeability is the other one. Rollup contracts are typically upgradeable by a multisig or a security council, which means the rules can change on a timescale shorter than any protocol change on Ethereum.
Why this changes nothing day to day and everything in a crisis
In normal operation a rollup feels like a fast, cheap Ethereum. The differences surface when something breaks: a sequencer outage, a contested withdrawal, or an upgrade you disagree with.
Knowing which assumptions you are accepting is the point. It is not an argument against using them — it is the difference between an informed choice and an assumption.
Supported rollups here
FBT Swap supports Arbitrum One, Base, Optimism, Linea, Scroll, zkSync Era and Unichain alongside Ethereum itself, plus non-rollup networks including BNB Chain, Polygon, Avalanche, Sonic, Mantle, Berachain and Monad.
The network is shown before every signature, because the same address existing on all of them is the most expensive source of confusion in multi-chain use.