Short answer
Freeze authority lets its holder freeze any wallet's balance of a token so it can't be moved or sold. For a memecoin, it should be revoked.
Freeze authority exists for legitimate reasons, such as regulated stablecoins that must be able to block stolen funds. In a memecoin, though, it gives the creator the power to stop you selling while they sell.
If it's still active, the creator can freeze buyers' token accounts at any time. That turns an ordinary-looking token into a trap. Like mint authority, revoking it is permanent and visible on-chain.
The DYOR rug check treats an active freeze authority on a memecoin as a serious failure, not a minor warning.
See the checks for yourself
18+ only. Self-custodial: you keep your keys. 0.5% per trade, no minimum. Memecoins can go to zero.