Why would that make any difference? What an employer spends on an employee is what the employee gets. If the employer spends less, the employee gets less, and hence is a pay decrease, even if not in nominal terms but in real terms.

Premiums for a silver plan can easily be $30k per year for a family of 4. If an employer decides to cover 70% of it instead of 80%, that is literally a pay decrease of $3k, not to mention possible changes in coverage, deductible, and oop max.

For example, the employer could keep the 80% subsidy, but increase deductible from $1k to $10k. Unless premiums go down a lot that is basically a huge pay decrease too.