Paraphrasing Basti from this comment:
The runtime upgrade to Polkadot 0.8.28
had the following migration: https://github.com/paritytech/polkadot/blob/371681c298eb96b74ad04a09ca8097f19c777e68/runtime/polkadot/src/lib.rs#L968
The second parameter to the apply
function was the old CandidacyBond
. It was passed as 1 DOT
while it was actually in the release before: 100 DOT
.
The result is now that some accounts only got 1 DOT unreserved, while it should have been 100 DOT.
This referenda calls Balances::force_unreserve
for the two accounts which had incorrect amounts unreserved.
See this issue for more information.