It’s probably fine. A DI usually runs into a mic preamp on the desk, which is designed to accept a very low level signal, and then be boosted up at the desk. Unfortunately there isn’t really an industry standard for DI outs from amps, so there are many that put out a much hotter signal (why some amps have options for output level at the DI, and many desks have pads to reduce hot signals or switch between mic and line levels).
I’d guess the engineer hadn’t come across a mic level output in a long time..and was expecting a much hotter signal.
I’ve been using an old AH150 a lot over the last couple of years - it’s got an old style transformer DI, mic level. No issues, except once where I was told it was noisy and quiet. Put a passive DI on the effects send and it was fine..but my guess was the engineer found the mic/line selector button while I set up the new DI 😜 and kept quiet..