I found another dapp on Mantle Testnet with confirmed incentives.
The projects is Galador. The incentives for testnet users are confirmed ( https://mirror.xyz/0x953ff5E816D86b305323C5317755C55026f1dF4e/nsOY13UzNl0ZaqGNVTMZ_x-41y-aONjSnYXJAfUSnXI ). Galador is another dex on Mantle network, which will be live on mainnet (I think they will launch on 17 July, but I'm not sure about it).
Guide
join in their Zealy camping https://zealy.io/c/galador/invite/eo-RqppE85yJTClxw6tt-
Go to their dapp and claim tokens from faucet (copy your tx hash because there is a tasks in Zealy about claiming from Faucet). https://galador.io/faucet
Do swaps MNT to USDC/GLDR; GLDR to USDC; USDC to USDT; (copy every tx hash and do Zealy tasks). https://galador.io/swap
Provide liquidity to GLDR/USDC; MNT/GLDR (again, copy all tx hashes) https://galador.io/swap/pool