Liquidity is not guaranteed for assets that a borrower would like to borrow, or a lender would like to withdraw on Proton Loan. The Proton Loan protocol relies on a fluctuating system of variable interest rates to attract lenders when liquidity is required and to attract borrowers when liquidity is abundant.
When there is high demand for a given asset and the liquidity of that asset begins to decline, the offered interest for the lender will rise to incentivize added liquidity. When the demand for an asset begins to decline, the offered interest for a lender will also decline. In this way, lenders are incentivized to meet the demands of borrowers as the demand for the underlying asset changes.
During high utilization events, while lenders may receive high APRs on their deposited assets, they could potentially be unable to withdraw their assets if their balance is higher than the excess liquidity currently available to be borrowed.