RTS process has a check to verify the restored update timestamp from the history store must be less than the on-disk version of the data store which is getting replaced due to either it is unstable according to the stable timestamp or a prepared update.

WT_ASSERT(session, hs_tw->start_ts <= unpack->tw.start_ts); 

This condition can wrong if a prepared update is written to disk and it has an out-of-order prepare timestamp compared to the committed update.