Cheap generic upscalers add significant latency and worse non-consistent latency. It might be OK for a turn based RPG like Persona 3, but it will drive you mad for games like DDR, Guitar Hero or heavily action based games.
The biggest issue is that some stretch picture IMO. The latency is greatly exaggerated IME. I just used an older TV with a built in good upscaler (newer TV have worse upscalers).
They have other issues too and RetroRGB has a good video going over the problems:
https://www.youtube.com/watch?v=ZUrqWN4AcJc
Not all TVs support 240p over component either, especially from the late 2000s/early 2010s which means you can run into problems with some PS1 games on a PS2 or earlier consoles.
https://www.hdretrovision.com/240p
These days there are clones of the RetroTink 2s and options like the ODV GBS-C that are decently priced and good options.