Not 50% anymore, the max deductible rate is now 43% and in 2023 it'll be 37% at which point there won't be anymore scheduled reductions. (but I'd be surprised if further reductions won't be announced the coming years).

It can be a misleading to say this means only 50% or 37% of your interest can be deducted. It could still be fully deducted. i.e. if your income is taxed at 37% rate, then the 37% rate of 2023 will mean your entire interest can be deducted from your income (100% interest deduction).

It means that at higher progressive tax rates for higher incomes, e.g. at 50%, only 37% of the 50% can be deducted.