You stated it's still the same entity. There would be continuity of tax returns for the entity, then. Just because there are old partners, there still would be no break between tax returns, but that's why I brought up the consideration of a short (or allocated) year.

You cannot get Guaranteed Payments from something you do not own. You are not entitled to that, unless you own it. You can get paid for other reasons (lender, employee, service provider, sales, etc). Maybe the prior CPA wasn't given the full story.

"when i did the first quarterly estimates during June 2021."

Estimate of what?

"I guess then it is up to the previous partners to report everything correctly on their 2021 personal returns."

There might be some required reporting on your taxpayer's part as a result of whatever this activity is (on 1065, on 1040), but don't mix perspectives.

"did I need to issue anything in 2021 from the LLC to the 2 previous partners."

Maybe. Perhaps your taxpayer is supposed to have something from 2020?