For Gzip, memory usage during decompression is bounded statically by 32K + constant decompressor overhead; for Zstandard, it’s 128M (tunable) on non-ultra levels (mentioned in the header); I don’t know about Brotli but it probably has something in that vein as well.

Brotli LZ77 window is at most 16 MiB (RFC 7932, section 9.1), unless you are using the non-standard Large Window Brotli extension in which case it is virtually unlimited.