Submitted by Ruhum, also found by TrungOre, MaratCerby, 0xBug, minhquanym, shenwilly, 0xDjango, remora, danb, IllIllI, pedroais, m9800, and hyh
https://github.com/code-423n4/2022-04-badger-citadel/blob/main/src/Funding.sol#L177
https://github.com/code-423n4/2022-04-badger-citadel/blob/main/src/Funding.sol#L202
https://github.com/code-423n4/2022-04-badger-citadel/blob/main/src/Funding.sol#L184
https://github.com/code-423n4/2022-04-badger-citadel/blob/main/src/StakedCitadel.sol#L769
The Funding contracts deposit() function uses the getAmountOut() function to determine how many citadel tokens the user should receive for their deposit. But, if no discount is set, the function always returns 0. Now the deposit() function tries to deposit 0 tokens for the user through the StakedCitadel contract. But, that function requires the number of tokens to be != 0. The transaction reverts.
This means, that no deposits are possible. Unless there is a discount.
Funding.deposit() calls getAmountOut(): https://github.com/code-423n4/2022-04-badger-citadel/blob/main/src/Funding.sol#L177
Heres the getAmountOut() function:
Call to StakedCitadel.depositFor(): https://github.com/code-423n4/2022-04-badger-citadel/blob/main/src/Funding.sol#L184
require statement that makes the whole transaction revert: https://github.com/code-423n4/2022-04-badger-citadel/blob/main/src/StakedCitadel.sol#L769
Change the getAmountOut() function to:
shuklaayush (BadgerDAO) confirmed 
