I had thought there was texture on the rendered wall, but it's also on the vertical blinds. It's hard to understand, especially with a photographer of Leo's quality.
Some things come into my head, all remote possibilities.
Anti-reflection picture-framing glass instead of Anti-Newton glass in the scanner's film holder?
I have found that dust removal software can do odd things to scanned silver images.
Is a Photoshop filter or effect accidentally switched on? I'm not sure how this could happen.
Is sharpening switched off?
Is there a glitch in the scanner software? Does it need updating? [My scanner produced astonishingly bad results after an OS update, until I updated VueScan too.]
Can the problem lie with "HP5plus cheap at a market"? Does it have the correct notch code?
Could you try HP5 bought expensively in a shop?
Could you try returning to ID11 or D76? I've not heard of them producing such problems.
Could you try a commercial lab for a few test sheets?
This might happen if a darkroom print on textured paper were scanned, but I don't think this is the case here.
That's emptied my tiny brain of all ideas, even very unlikely or silly ones. My apologies if some of them seem insultingly simplistic. That's not my intention; I'm trying to cast as wide a net as possible.