When I was unhappy with my PF tightness, I've developed solution to slightly lower pf holder's wall edge to get the baskets sit a bit deeper and decrease tightening force in the grouphead.
I've got a sheet of relatively fine sandpaper (800), fixed it on the flat hard surface and by circular actions (with basket removed of course) grinded off some height of holder's wall. Maybe one mm or so. Exposed brass is invisible with basket installed and I have no issues with this for a few years so far.
There is a small tolerance here, half of mm giving big effect on the locking position. I've measured several times with all my baskets through the process.

Since the action can't be undone, before going for it I've verified similar behavior for this holder with all my baskets/gaskets while other holders were ok, and the problem exactly with this one.
My justification was exactly to avoid grouphead wear and increase safety by properly locking pf.

For sure you will lose your warranty on the holder, so better to check replacement option with your supplier, because there is a chance that your holder is slightly off the dimensions. Even thicker coating or other surface finishing issues on basket contacting surface could contribute to locking problems.

Thank you all for the thoughtful replies. I am playing with the idea of sanding (with very fine sandpaper - 1500 or 2000 grit) the wings of the portafilter, so that I can smooth them out without affecting their thickness or shape. I think this will get rid of the accumulated brass on them (it is not exposed brass, as the PF is stainless steel).
I am also considering doing the same to the inner threads of the grouphead where the PF locks (now this I am a little more reluctant to attempt), thus removing the chrome that will be stripped away in time anyways, while polishing the threads. Maybe that is not a good idea, but it seems like the thread wear is uneven.