Well considering Trump has a long history of not actually paying his employees, wouldn't be surprised if this guy couldn't afford it

On review of all the additional evidence and testimony, it became obvious to the prosecution that the key witness ("Trump Employee 4" - revealed by NBC News to be "Yuscil Taveras" - IT Director at Mar-a-Lago) in question had perjured himself in earlier grand jury testimony and that it was a conflict of interest for that witness to be represented by by the same attorney (Stanley Woodward) representing other involved clients.

Prosecutors asked for a hearing on the representation issue before James Boasberg, the chief US District Court judge in Washington DC who oversaw the grand jury investigation.

Judge Boasberg had a federal defender available to advise Taveras if requested, and Taveras did opt to change lawyers after he learned he was being investigated on suspicion of making false statements in previous grand jury testimony.

So, TL/DR: he went with the public defender out of the immediacy and need for independent counsel and the only option available at that moment was the public defender who was pre-emptively made available by the Judge himself.

I will speculate that he will be acquiring his own representation going forward.

He probably can't afford it

Probably was offered immunity, but his Trump paid lawyer said no. So why spend money on a lawyer when you can get a public defender for free and then take the deal?

Idk but possibly related: I've heard that there are a good number of times you should prefer public defender to paid representation.

Perjury to advantage his other client. There has to be a law against lawyers doing that.

You could argue he wasn’t the guy’s lawyer

who was being paid by the former president's Save America PAC

A lawyer represents whoever is the paying his bills.