Renown and Repulse were razeed on the stocks, not in service

Could Renown and Repulse be considered the last razee frigates?

Only loosely: they were radically redesigned before completion, but never served in an earlier form and were officially treated as battlecruisers.

A traditional razee begins as an existing ship and is cut down into a different form, whereas Renown and Repulse were altered while still on the stocks. Their redesign can therefore be called razee-like without making them literal in-service conversions. Fisher's choice to call the type battlecruiser rather than battle frigate also shaped how later navies understood its place in the battle line. A different label might even have complicated Washington treaty categories by separating the ships rhetorically from battleships and battlecruisers.