The well-known disassembly website iFixit has disassembled 2024 13 inch Apple iPad Pro 256GB version, which is equipped with 9-core M4 chip and 8GB memory 。
The disassembly drawing shows that the 8GB memory iPad Pro uses two memory particles with silk screen printed as "Z8DMS", and the particle model is "MT62F768M64D4AS-026 XT: B" through querying the official website of Micron.
According to the official website of Micron, "MT62F768M64D4AS-026 XT: B" is a 768Mbit x 64 (48Gbit) memory particle with a capacity of 6GB. The material purchase website shows that the memory is LPDDR5-7500 and packaged with VFBGA. This indicates that the 8GB memory version M4 iPad Pro actually uses 12GB memory particles.
Related reading
https://www.reddit.com/r/hardware/comments/1cvq1rs/do_m4_ipad_pros_with_8gb_of_ram_actually_have_12gb/
https://forums.macrumors.com/threads/do-m4-ipad-pros-with-8gb-of-ram-actually-have-12gb.2426801/