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Since Solidity v0.8, the compiler has checks for {over,under}flow by default for all arithmetic operations.

Do these checks apply to assembly (yul) arithmetic operations too?

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No, they apply only to non-assembly code. Check for yourself on Remix:

// SPDX-License-Identifier: MIT
pragma solidity >=0.8.0;

contract Mul {
    function mul_normal(uint8 x, uint8 y) external pure returns (uint8 result) {
        result = x * y;    
    }
    
    function mul_assembly(uint8 x, uint8 y) external pure returns (uint8 result) {
        assembly {
            result := mul(x, y)
        }
    }
}

Passing 255 and 2 as x and y, respectively, reverts when calling mul_normal but yields 254 when calling mul_assembly:

Remix Screenshot

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