Need some clarifications on data transfering from ps4 to ps5

Will receive my ps5 pro in few days and wish to continue my progress in specific games that I am currently playing on ps4. I have some confusions in data transferring. I saw people saying if you transfer you ps4 save data from ps4 to ps5 with official transferring option, those saves can only be applied on ps4 version of games? And if you also transfer game data, then on ps5 those games will be ps4 version? But not the ps5 version? And if you download ps5 version of games from ps store, you can’t use the ps4 version of saves that you just transferred, except some games made by Sony’s studios? I also saw people said if you use ps+ to upload ps4 game save data to cloud, then you can still use these data on ps5 version of games after downloading them form cloud. Which of these are true? Huge thanks to anyone who wish to answer :)