As an example, if you have accrued 100 share seconds and the total pool has 500 share seconds, a 2x multiplier would adjust those values to 200 / 600, giving you 33% of the pool instead of 20% (100 / 500).
As an example, imagine there are 400 tokens staked in the pool. If you stake 100 tokens and apply $GYSR to receive a 2x multiplier, instead of earning 100 / 500 (20%) of future rewards, you will earn 200 / 600 (33%) of future rewards.
An example would be if a project decided they wanted to incentivize 90 days of staking, they could set up a 50% penalty at the start. If an investor unstaked after 45 days, they would be halfway through the penalty period. Halfway between 50% and 100% is 75% so the investor would only receive 75% of their rewards. The remaining 25% would be redistributed to other stakers.