macOS 11.0 Big Sur compatibility with Mac Book Pro 2013
Yes, this in fact is an existing restriction with Catalina (see screenshot). It is unsurprising that the version of Mac OSX after Catalina has the same limitation; ultimately the hardware gets left behind as it becomes incompatible with changes in the OS.
See this table from https://eshop.macsales.com/guides/Mac_OS_X_Compatibility:

EveryMac lists the specifications of the Early and Late 2013 MacBook Pros at https://everymac.com/systems/by_year/macs-released-in-2013.html