RPi4 is excelently supported, but DVB is an icky topic regardless of hardware. The general recommendation is to separate tuners from the playback device so you can run whatever OS and hacked version of drivers and firmware that works reliably .. with playback on something simple that you can OS bump whenever LE puts out a new release. The moment you put both functions on the same device you can have a reliable player or DVB that works; they are generally mutually exclusive and you have to chose one.
That means you could revert to a legacy image, e.g. CE or dtech's LE 9.2.8 one for the TVH side. RPi4 is a nice playback device if you can get your hands on one.