What is the ruling on a rental method in which the tenant pays a large sum to the homeowner, then resides in the property for a specified period, and then reclaims the full amount after the period ends?

If the intent is that the amount is held as collateral, for documentation and as a guarantee for any rights that may arise from the tenant, then there is no prohibition in this, and the landlord must not invest this amount or benefit from it. However, if the rent for the dwelling is the landlord’s investment of the amount and the profits resulting from it, then this is impermissible due to the ambiguity (jahalah) and uncertainty (gharar) involved, and because it is a loan that draws a benefit, which is usury (riba).