Read on Twitter
1/ Funds on a Rollup should be as safe and censorship resistant as on L1. If you have $DAI on Ethereum, you own a coin that can only be minted by supplying collateral to MakerDAO. There is no other way. Let's explore a @0xPolygon side-chain to see the difference 
2/ When you deposit $DAI to Matic PoS Bridge, you send it to https://etherscan.io/address/0x40ec5B33f54e0E8A33A975908C5BA1c14e5BbbDf. You can see that there is 4.8M $DAI sitting there - including yours
3/ On the other side of the bridge validators will mint "DAI" token - 0x8f3Cf7ad23Cd3CaDbD9735AFf958023239c6A063. You can inspect its code here: https://explorer-mainnet.maticvigil.com/address/0x8f3Cf7ad23Cd3CaDbD9735AFf958023239c6A063/contracts
4/ As you can see the "DAI" on Matic is an upgradable contract. The real $DAI on L1 is not - nobody ever in the future can switch real $DAI from the current, permissionless token to sth less secure
5/ But the "DAI" on Matic can be upgraded by its current Owner, i.e. 0xdcFAE11C70F1575faB9d6Bd389a6188aE5524A56. Whoever holds PK to this address has the power to mint themselves unlimited amount of "DAI" on Matic
6/ The Matic "DAI" can then be withdrawn taking your (or somebody else's) $DAI from the bridge. And it is possible than when you want to exit to L1, there will be simply no $DAI in the bridge left for you
7/ So you are at the mercy of one address, 0xdcFAE11C70F1575faB9d6Bd389a6188aE5524A56. This is very different than holding $DAI on L1.
