The 2018 Idaho Form 40 instructions lay out the tax tables, which agree with TurboTax. It shows $3,205 as the tax for a single taxpayer earning between $50,000 - $50,050 (so exactly $50,000 would compute to slightly less - or $3,203).
You can view these tables at this link below -
https://tax.idaho.gov/forms/EIN00046_01-07-2019.pdf
This calculation ($3,203) also agrees with the brackets posted at the second link below on the site -
https://tax.idaho.gov/i-1110.cfm
Your second calculation appears to mix parts of the single bracket with the married filing jointly (but not entirely). You should be able to post a link to a URL if you respond to this answer in a comment. If you want to post the link there, I will take a look at wherever you found that information just for clarification - but the tax tables themselves agree with the first calculation.
