I'm in the US and have a private healthcare plan with low deductible. I'm wondering what the US industry standard is for handling my following situation.

1) I finally received a bill at the end of December 2022 from health services I received in the second half of calendar year 2019. I paid this bill on 1/1/2023. Would this out of pocket expense (OOPE) count toward my 2023 deductible and OOPE, or would it count towards my 2019 OOPE?

2) I had a different insurance company in 2019 than I do now. Do I submit the expense to them or my 2023 health insurance company?

3) If I met my OOPE max and deductible in 2019 and this bill counts additionally toward that calendar year, should I expect a refund from my 2019 health insurance company?

PS- I was hoping this bill would never arrive, then it would be void due to my region's statute of limitations. /s