You're right about the lack of a one time penalty. It used to be 6% of the excess contribution per year as long as it remained an excess contribution, which is usually enough of a penalty to cause people to remove it.
I think there is a way to carry it forward and treat it as though it was a 2021 Roth contribution, but that would probably involve the 6% excess penalty for 2019 and 2020, so probably not worth it.
If you recharacterize, the nice thing is you don't have to worry about the excess earnings. The drawback is if you're not entitled to the IRA deduction on your taxes, then you have basis in your traditional IRA. Having an IRA with basis is a multiyear record keeping issue that I choose to avoid. The other option is to do the recharacterization, take whatever tax deduction you can get, and forget about the basis. You'll pay slightly more taxes when you take money out of the traditional IRA many years from now, but you won't have to bother with the accounting.
Might not be any need to amend the return, but simply file form 8606 instead.
If FDC319 wanted to take the deduction for their 2019 traditional IRA contribution, Form 8606 would not be sufficient. This would also be true of the retirement savings contribution credit, although I suspect FDC319's income is probably too high for that.
I'm not sure if FDC319 would have to file an 8606 with the amended 2019 return - they may need to do so. FDC319, check the instructions for Form 8606.