GPU devices are very popular in mining cryptocurrencies but the ASIC devices usually outperforms them in many cases. The ASIC device usually consumes less power and has better hashrate.
The MicroBT Whatsminer M21 was produced by MicroBT and released in 2019. This miner consumes 1860W, producing 31.0 Th/s of hashrate with the sha-256 algorithm, which makes this device almost (if not at all) useless. We do not recommend buying this device for mining nowadays.