Addendum to my own question. This only happens if I enter any months under full time. If I enter them under part time, the refund goes up as expected.  So there is something wrong with the calculation if full time months are entered.

Can you please advise us if you are using TurboTax Online or TurboTax CD/download version?

I am using Turbo Tax online in Canada. I have duplicated the error multiple times by moving the months of study number from full time to part time on 2 different T2202A forms.  When anything is in the full time box, the calculation is incorrect.

The reason for this is, if you worked and have a T4 and go to school part time you might qualify for the Canada Workers Benefit- but if you go to school full time you are not allowed this credit which would make a big difference on your income tax refund. 

Thank you for choosing TurboTax.

The same thing happens here, but they do not qualify for the Canada Training Credits because they are younger than 26.  

@RafiS What likely happened is that when you put in your T4, TurboTax claimed the Canada Workers Benefit (CWB) (aka the Working Income Tax Benefit) for you. This is a refundable tax credit for people who work, but don’t make very much. However, students are usually not eligible for this credit, so when you added your tuition, then the CWB was removed, lowering your refund. 

The Canada Workers Benefit and Canada Training Credit are two different things. The Canada training credit (CTC) is meant to help Canadians with the cost of eligible training fees.

There are $8,000 in FHSA contributions for 2023. Claiming it vs carrying it forward does not make much difference in the balance (a benefit of $241.33 for claiming it). I am guessing this is because of the low marginal tax rate. 

@RafiS Taking the FHSA deduction is optional. You can take only what you need this year (or nothing at all) and carry forward the deduction for a future year.