The ratio between the combustion engine and the battery is currently 50/50, when it's not 50 and 0 because the battery is empty. That has led to a number of inconveniences. Among them, cars that accelerate crazily but eventually lose speed along the straights when they run out of battery.
In 2027 the ratio should be 60/40 with a slightly more powerful combustion engine or less battery and the plans for 2031 are to go back to a v8 engine with green fuel and probably a KERS like in the early 10s.
So BYD will probably never be in F1. Maybe Formula E?
btw Red Bull produce no cars at all, yet they are still in F1 and MotoGP, by your logic they should never be in motorsport if we go by produced engine types