You can see most of this information on CrowdProperty's site. The average borrower contract rate in 2020 is 10%, while the average lender contract rate this year has been 7.9%. I don't think they specific borrower rate on each contract but you'd conclude that given the historical record it's lender rate +2%, with minor variances.
It is an FCA requirement that they disclose the borrower rate to lenders, introduced in PS19/14. This information does not appear in the loan "Factsheet". You should at least be able to receive the information if you request it.