The penalty info is in the instructions you linked:
Penalty for Not Filing
If you are required to file Form 8606 to
report a nondeductible contribution to a
traditional IRA for 2019, but don’t do so,
you must pay a $50 penalty, unless you
can show reasonable cause.
John and kjpliny -- yes, you are required to file an 8606 if you made a non-deductible contribution to a tIRA or if you converted part or all of a tIRA to a Roth (or if you did both in the same year, which is your situation). You should have received a 1099-R from the tIRA custodian with a code "2" in box 7, and when you enter that data into TTax it will ask what you did with the money. Choose the option that says you converted it to a Roth IRA and TTax will automatically generate the correct 8606 for you.
I am a little surprised that the IRS hasn't generated one of their automatic letters asking about the 1099-R that you didn't report, but maybe they don't bother if it's got a code 2 on it. It seems unlikely that they are going to dig into old returns for no reason, especially if it there's no reason to suspect that you underpaid the tax due, so I'd probably just let the past go and do it right from now on. If they ever do complain, you can apologize for the oversight and request a waiver of the penalty.