This has happened in the past and may happen in the future. When the sequencer comes back online and oracles update their prices, all price movements that occurred during downtime are applied at once. If these movements are significant, they may cause chaos. Borrowers would rush to save their positions, while liquidators would rush to liquidate borrowers. Since liquidations are handled mainly by bots, borrowers are likely to suffer mass liquidations.

This is unfair to borrowers, as they could not act on their positions even if they wanted to due to the L2 downtime.

Hence, it would be ideal if your protocol gives borrowers a grace period once the sequencer returns.

Source:

https://0xmacro.com/blog/how-to-consume-chainlink-price-feeds-safely/

Mitigation steps:

https://docs.chain.link/data-feeds/l2-sequencer-feeds#example-code