Previous company had HSA, new company has FSA, want to go back to using old HSA

I left my previous company in 2020, which had an HSA, and started contributing to the new company's FSA in 2021.  There is no company match. I am still in a high deductible plan. 

 

I want stop using the FSA and want to resume using my old HSA in 2022,  but only if I can still get HSA tax benefits.  I envision just using after-tax money to fund the HSA, and then claim the HSA contributions on 2022 taxes to reduce taxable income.  I see all sorts of statements that say the HSA 'belongs to me' and I can use it as long as I am under a high deductible plan, but - I can't see anywhere that says that contributions can be used to reduce taxable income like an IRA would