Another said it, but I'll repeat it: If you take the lump sum, all your benefits stop immediately. For many, that is huge, as you might currently be paying, say, $250/month for health insurance through the company and could see it skyrocket to $1200/month if you switch to COBRA or perhaps $700/month via ACA coverage.
As for the tax impact, that's going to depend on years of service. If you get laid off in mid July, the end of the notice period will be around mid September, which would be about 7 pay periods. Since the severance is 1 pay period per year of service, the tax impact would likely be a wash if you have under 7 years of service, but would potentially be more in your favor to not take the lump sum if you have over 7 years.
Another option would be suppose you had 20 years of service and get laid off in a couple weeks and it takes until around the end of this year for you to get a new job. In that case you'd be on your new company's benefits by the start of 2024 and still have perhaps 13 WF severance pay periods left. Once in 2024 and on your new company's benefits, then it would potentially make the most sense to just take the WF lump sum for the remainder.
WF lets you switch from regular pay to lump sum at any time in your severance, but once you make the choice, you can't undo it. So the safest time to take the lump sum is only after you've started your new job or gotten on your new health insurance one way or another.