Once upon a time doing something like mixing video card types would have been frowned upon, but those days are long gone now. Developers have had over a decade now to implement all sorts of feature into their mining software that enable you to do lots of things like mine multiple coins or as you asked about, using different types of GPUs.
Now only beginners are trying to assemble mining from different video cards. I don’t see any problems with this, but it’s not very convenient from the point of view of settings and maintenance, if, for example, one video card heats up more than others because it is more powerful.
If I’m putting together a rig, I always take a set of video cards for a certain power supply in order to use the equipment with maximum efficiency.
I would still suggest you do buy cards from the same manufacturer at least even if there are different series as this is my personal experience,I have had a rig with 3 AMD GPU-s and 3 NVIDIA GPU-s which worked fine for most of the time but the driver updates of either side put me in a bit of down time rarely until I installed the updated drivers and this was with trial and errors to see what was the problem.
I now own a personal rig with 3 cards at home as we split the partnership since Ethereum moved on Pos on September 2022 and since then I am running a Rtx 3060 ti,a Rtx 2060 12 GB and Rtx 3060 12 GB all running perfectly fine and the temperatures are near the same with the 3000 series just 2 degree Celsius more as they are more powerful cards.I have no down time with these cards.