I've noticed a marked change in trading patterns across my share...

I've noticed a marked change in trading patterns across my share portfolio from about a year ago. Most notably bots operating in stocks previously unmolested. I think this coincides with a reported increase of Millenials now turning to stocks as they feel locked out of housing and so seek somewhere for their marginalised deposits. This seems to have caused a lot more short term trading with people dumping out of stocks on only modest (10-15%) gains.

This by itself doesn't suppress a stock too much but I think this change in behaviour has allowed algos to do much more effective tree-shaking as less and less long-term/confident holders give way to "weak hands" who are only dipping in for a quick kill. That's probably a but overwrought but I can't think to explain the shift in performance style since 2016..