we can't see your return. on the 8889 what line has the $5271. was the correct type of coverage selected for each month?
If you and your spouse are both HSA-eligible individuals and one of your has family HDHP coverage, both of you are treated as having HDHP coverage. Perhaps this applies to you and TurboTax is determining the amount that you are eligible to contribute after factoring in the amount that your spouse has contributed.
I don't see my return either. I have no idea what is on the 8889 before the whole return is finalized.
I believe it does not matter, whether you can see my return or not. The IRS limit for the HSA contribution for a self-only HDHP plan is $3550, plus $1000 for a person age 55 or older. Therefore the only reason why TurboTax can calculate the amount bigger than $4550 is a bad math, isn't it?
The coverage selected is "Self Only" for for Jan-Oct, and "Medicare or None" for Nov-Dec, which makes the pro-rated maximum even lower.