The escrow is designed to incentivize guilds to pay back investors as fast as possible. When guilds distribute dividends, their 15% share is initially sent to an escrow wallet which is unlocked only when 100% of the capital they received from investors is returned through dividends. Guilds are likely to maximize dividend payout so they can access their accrued dividends as quickly as possible. After the escrow is unlocked, they can immediately access 15% of any dividend payout without sending it to the escrow first.
In V1, the escrow is a multisig wallet with address 0xF31BE6574c5cd42C35B57b6Ddc64559ddAb73284 that is controlled by the pool manager (OpenGuild Finance). Guilds are contractually obligated to send their 15% share of dividends to the escrow wallet until it is unlocked. The pool manager will keep track of dividends paid back to the pool and send guilds their accrued dividends when they meet the escrow unlock requirement.