I think this is the salient point. Hospitalisations is the thing to keep an eye on.
If you look at the current 7-day average for infections, the last time we were at this level (on the way up) was around Christmas. At that point in time, we were experiencing an average of 475 deaths per day, compared with about 37 per day now.
It's a bit of a false comparison, as we'd already had a mini-lockdown in November, which suppressed infection rates for a few weeks, but you still had a reservoir of hospitalisations during that period, some of which would unfortunately later translate into deaths. Notwithstanding that, it's still accurate to say that the relationship between infections and deaths has been significantly weakened compared to the 2nd wave.
However, if you look current hospitalisation data, we currently have a 7-day average for admissions of 562 per day, a total of 3,786 people in hospital and 545 patients currently on ventilators. If you look at the last time we had comparable numbers during the 2nd wave (again, on the way up) it was in early October when we had 573 admissions per day, 3,893 people in hospital and 442 patients on ventilators (so pretty close to the same proportions as now). At that point in time, the 7-day average for deaths was about 53 per day (compared with 37 per day now).
So the relationship between infections and deaths does appear to have been significantly weakened. However, the relationship between hospitalisations and deaths, which may have been weakened slightly, does appear to still be there.