has a feature in Barron's, https://www.barrons.com/articles/actively-managed-etfs-51648674407?mod=past_editions
My summary from LINK
FUNDS. The number of actively managed ETFs (846 now) has grown significantly after the SEC rule changes in 09/2019 (Rule 6c-11 for SEMITRANSPARENT ETFs). Yet, the largest active ETFs are still small by AUMs (DFAC, ARKK, DFAT, DFAX, DFAS). The ETF clones of active mutual funds remain tiny: FMAG/FMAGX, etc. But several restrictions (intermarket exchange trading, etc) are hampering the growth of these active ETFs for funds that may hold foreign stocks, bonds (even though most active ETFs before the rule change were active bond ETFs), preferreds, etc. Their ERs are also high. American Funds and Harbor Funds have introduced self-standing active ETFs that don’t pretend to be clones of existing mutual funds.