I share the concern. I own AAPL, MSFT, AMZN, and GOOG (BRK too) separately from my index funds so I don’t need to own more. Those five stocks are about 35% of my portfolio.
So I hold QQQE instead of QQQ. As @Hawkwin points out, it has been underperforming QQQ the last several years, but I think you could make a reasonable argument it is a better value at the moment. Maybe not, but I’ve got about as much large cap tech as I want. In addition to VTSAX (total market), and I have good slug of VO (mid-cap) and some small cap as well. So I’m more like equal weight for the S&P as well, as far as index funds go.
It should be noted that mid-caps have been underperforming large caps in general lately, not in just in tech. So there is that.