You still need to deal with the Excise tax on it. You can typically handle it one of 3 ways: get it back, leave it and pay the penalty tax, or allocate it until it is absorbed to future years.

I find great resources for these from the investment companies all over the web. Her's one:

https://www.investopedia.com/articles/retirement/04/042804.asp

Oh: "I know when we make SEP contributions the bank doesn't actually apply them to a particular year (like a traditional IRA) its up to us to decide which year they apply to."

I'm pretty sure you are supposed to identify it as Current Year or Prior, so that 5498 shows which year it applies to.

Was it paid in 2019 or 2020?

You dont, I even verified with my bank, they told me they dont care what year its for, they post it in the year its made, its up to me to decide which year its used for.  Its not like a trad IRA, where you have to specify the year its for,

"so I should be able to allocate the overage to the 2020 tax year, right?"

Yep.

Yes.