Different Tg values will affect the final PCB prototype manufacturing costs. In other words, you have to pay for the Tg value of the PCB board.
FR4 is one of the most popular materials used to make PCBs. FR in FR4 stands for flame retardant, whereas the number 4 differentiates the material from other materials in this class. FR4 is a fiberglass-reinforced epoxy laminated sheet, which looks like a thin, and woven cloth sheet.
High Tg PCB is the right choice for electronic equipment under a high-temperature environment, which can make electronic equipment play its performance better under a high-temperature environment. High Tg PCBs are also used in other top-temperature products.