Taxes have been held for over 5 years but what I owe hasn’t been paid on. Why not? That’s the point of withholding them isn’t it??

[Opus 17]

Your question is not clear, please explain more.

Each year is treated on its own.  You are required to file a tax return for (let's say) 2020, that reports all your 2020 income and deductions and calculates your tax owed.  If you had withholding, the taxes you already paid (by withholding) are compared to the tax you owe, and if you under-paid, you owe more money when you file, and if you overpaid, you get a refund.  The process repeats for 2021, 2022, etc.  Taxes withheld from your wages for 2022 are applied first to the taxes you owe for 2022, not to past-due tax debts.  If you owed a large tax bill from (for example) 2020, and you didn't pay it, then any refund from 2021, 2022, or 2023 could be held back to  pay the past due bill.  But before that happens, the actual tax you owe for 2021, etc. must be calculated on a tax return so the IRS can determine if there even is a refund to use for back taxes.