I have just received the last 2 posts as an update to a post re this problem which I also suffered from in 2018. I didn’t know this was still a problem. I had this back then, casting from iPad to Chromecast. Now TV game up with a fix back in 2018,and since then I haven’t had any problems casting from iPad.
This new problem seems to be PC based only? Maybe try casting from another type of device to see if it works better, then it may be easier to isolate it to a PC problem.
It does not do this with the NowTV Stick only on NowTV player on windows (not MS Store version of the app) not sure about chromecast as we do not use this anymore - but had the same problem originally back in 2018 (as described earlier in the thread) my assumption of it being 'fixed' after three months is potentially whatever advert caused the crash ended its run naturally.