The disadvantages of Solana Pay include the fact that both Solana Pay and the Solana network as a whole are still in their infancy.
Businesses that switch to Solana Pay run the risk of losing their assets as a result of, for example, a network attack or programming error. Because managing a cryptocurrency wallet isn't easy for everyone, it's possible for the company to lose assets as a result of simple user mistakes if they aren't familiar with the technology. Likewise, while Solana is quicker than a significant number of its rivals, Ethereum is as yet a lot greater, generally speaking. Solana's user base and number of DApps are significantly greater on Ethereum than on Solana's, and Ethereum's eventual transition to Ethereum 2.0 may also be problematic for Solana.