I have chromecast, chromecast ultra, chromecast with google tv, and a sony tv with chromecast - all of them work fine with my WRT32X running 19.07.6 (and all 19.07.x versions before that)
Not quite stock version of openwrt, I've added one thing to startup
echo "0" >> /sys/kernel/debug/ieee80211/phy0/mwlwifi/tx_amsdu && echo "0" >> /sys/kernel/debug/ieee80211/phy1/mwlwifi/tx_amsdu
I can't recall what that does to be honest - got it from Linksys WRT1200AC wireless performance on latest stable