Proposed BIP for OP_CAT

The email discusses the stack element size limit in tapscript. It mentions that in the current age, tapscript enforces a maximum stack element size of 520 Bytes. The author questions whether there is a new limit related to tapscript. They mention that initially there was no limit, but a 5k limit was put into place. This limit was then reduced to 520 in the same commit where OP_CAT was disabled (commit: 4bd188c4383d6e614e18f79dc337fbabe8464c82).