Over the last short while I've regularly checked redemption, Business availability in September and October 2021 for LHR to Tokyo. There has been plenty. Few had limited numbers. Day after day there were at least 2 seats. Thursday was my preferred off peak day.
I was also keeping an eye on the ba Reward Flight Finder site.

Today I knew the dates I can travel and went to check. Alas it's almost all disappeared and the few flights are either too early to connect from BHD or only single seats. JAL is offered but of no use at it was to use my extended Lloyds Upgrade Voucher so needed to be BA.

Could this be connected to the sale? Would ba reduce Avios availability during one?