Roth 401k & Super/Mega Roth Opportunities

[Pixel Rogue]

Hello everyone,

Due the number of assumptions made around the more known 401k rules and limits, respectfully requesting responses to be from those who are intimately familiar with (rather than google'd it and have an opinion) how Super/Mega Roths work with standard familiar employer based Roth 401k plans in the same year (but not concurrent.)

SITUATION
I have been an independent contractor and fortunate in being able to contribute to retirement via Mega Roth conversion. That contribution has been maxed out for 2021. I recently accepted a full-time position and am no longer an independent contractor.

QUESTION
Since I was independent FIRST, and the contribution was made as after-tax funds to a qualified traditional ira (then converted,) am I able to contribute in 2021 to my employer sponsored plan?
Note ~ I understand one can not contribute to both 'concurrently' - one can not contribute to both an employer sponsored plan and independent plan at the same time.