To avoid this, you want to have a multifaceted approach.

Figure out how low your expenses can be while still being quite happy with your qualify of life. Some expensive things don't provide the happiness you think they will.

Diversify the kinds of investment accounts you have. Maximize your tax-advantaged accounts like a 401k, but then contribute to a Roth IRA if available, and then plow money into a taxable brokerage account. When you approach retirement, plan to have some time period of expenses covered by cash on hand.

Then use cash, brokerage and Roth funds to cover expenses, while converting what you can from 401k or traditional IRA into Roth funds, and minimizing the income/taxation that results so you can still qualify for credits. Funds converted to Roth will be available for tax-free withdraw after 5 years, so continue to convert over time, while using the post-tax accounts to cover expenses.

This and HSA is nice to have as well. Max that out. Pay out of pocket for everything and keep records of it. When you retire you can pull all that out tax free. Irs says you can can do it. And it is pretax. Any left over money will turn into IRA when your old. But if you have family and can cover the out pocket cost HSA are really nice extra amount. My plan is use my taxable and withdrawal medical expenses from the hsa tax free. So I can convert 401k funds to Roth using the ladder. Ideally the normal Roth I have had for years never gets touched for a long time. Also you can also do a Roth via backdoor.

This assumes all of your income comes from a traditional 401(k). As an early retiree that's unlikely. It's likely that a significant portion of your income will come from a taxable brokerage account. A significant portion of that income is your basis (what you paid for the investment) which is not taxable.

There's a lot you can do to "engineer" your taxable income in early retirement.

> If you withdraw from a 401k, doesn’t that become taxable income?

Currently, if you're married, the first $24K or so is tax free. If you're in California, there are plenty of credits/deductions, so it's likely more than $24K.

Also, you can have a 401K Roth, where all withdrawals are tax free.